Downloaded pictures often corrupt. Got any suggestions?

Thought I would pass this problem by the forum for any input, as you are also seeing some of these same photos, and may have some additional suggestions for me to try.

When I download photos posted in this forum, either as part of a simple page loading or as a separate image only download to view or edit, the picture I obtain onscreen is very often corrupted... sometimes only parts of the photo arrive, sometimes the segments are streaked, or the segment of the photo are not assembled in the correct order to create the image correctly. I realize not all of the photos are embedded in the web page and that some are pulled in from Photobucket, Flickr, etc. It does not seem to make a difference.

To no avail I have (many times) rebooted the computer, flushed all computer caches I can locate, tried both Firefox and Internet Explorer, run Memtest on the memory, relocated Pagefile and increased Page file size significantly, Also had the cable company to the house several times which resulted in no change even after twice changing out the modem and incoming cable. I have also swapped out the wired router twice, bypassed the router, used a new Intel network card in place of the built-in LAN, and even tried different computer. So far no sign of real improvement, and all perceived improvements are very shortlived and do not point any specific direction path to pursue further.

The two main computers in my office are fairly new and powerful units, running Vista 64 bit and Win 7 64 bit. Computers have 8 and 12 GB Ram, not overclocked and run at 3 GHz very stable 24/7, with many terrabytes of free disk space. Only seem to have problems with image downloads from the internet. My regular photo processing is not a problem.

If you have suggestions I would appreciate hearing from you. I realize this is not a "computer forum", but at least you are working with the same materials and might have relative experiences.

Thanks in advance.

Is it only images that corrupt, or do other things not work properly? Do downloaded executables always work? Do you get many blue screens? Does it happen with images you take yourself? Do you use antivirus? What plugins and web browsers have you tried?

Thanks for the reply. So far it seems only images are a problem -- have not observed any errors in general text files, letters, or even my income tax reports.

Images over approximately 300KB are corrupted most of the time, but smaller images are also screwed-up at times. Small examples may be the images like your facial icons posted at the left side of this sites web page, or the small photos included in news announcements on a web site. Large photos from this web page, embedded or imported from host sites, are very frequently corrupt. When a member posts several photos in a post, all or just a few may be corrupt.

If a download photo is large, say 300KB to 3+MB, it will almost certainly be corrupt or incomplete, showing perhaps 10% of the image. Note that photos downloaded from the camera cards are NOT affected -- ONLY internet downloads involved. So the corruption occurs either before the download on the host site's server, during the download path, or in the reassembly of the downloaded blocks in my computer by the software.

I have also played musical chairs using three different video cards, but the problem does not seem associated with any particular card. The cards all have 1 or 2 GB video ram. I use Zone Alarm on three computers here, and Avast on two others. Problem occurs whether using an AV or not, and with both AV programs. Computers have all been screened for virus and malware many times. And there is NO social networking allowed on computers in the house (Facebook, etc) to reduce risk of infections.

I am really wondering what involvement my cable ISP may have in this since their service has not always been great, but several other local photo buffs using the same service have not noticed this problem (admittedly in different neighborhoods). But the cable service has been to my home several times and cannot improve the situation.

What is perplexing is that the problem started on all the computers about the same time last fall, and nothing was changed here physically at that time, or other software added. Normally I use the computers for different major tasks with one computer designated for photo processing, which is where I noticed the problem first. After several days of frustration, I started using another very capable computer for the task to prevent getting behind, but then noticed the problem there also. The other computers do not really get involved in photo work, except for brief tests while trying to sort out this situation.

At the moment I am running out of ideas. Also am not currently building another computer so I do not have a absolutely clean fresh build to compare to the seasoned computers. My number one photo computer is one year old, its backup computer is two years old.

Sorry this is so long, but hope explaining my setup and efforts already tried may lead you to suggestions I have missed.

This is pretty odd. I doubt it's your ISP, since other downloads are working fine. TCP is a pretty reliable protocol, so I think it's your PC.

Try uninstalling zone alarm and see what happens. If that doesn't help try yourself a trial of a VPN service like Astrill and see if the problem occurs if you download over the VPN instead of direct over cable modem - VPN is an encrypted tunnel and your ISP won't be able to alter it. I doubt it will make a difference but it's worth a go.

When you say images are corrupt, how can you tell they're corrupt? Viewing them on a web page? What if you right click, download, and view with photoshop or irfanview?

Also what web browser(s) is this on, and what plugins do you have installed in them?

WoW! That was a fast response!

Have not uninstalled any AV program yet, but have turned them off and had no difference.
Really hate to uninstall Zone Alarm as the multi-year multi-pc re-install and license re-activation gets pretty complex with that company. I could uninstall Avast on one computer but as noted just deactivating Avast made no difference.

The VPN trial may be a very good next step if just to eliminate the ISP from being in question! This might take until next week or so to get organized as my time and schedule is pretty tight currently. ISP remains under suspicion due to slow downloads, frequent outages, and the fact I am seeing problem on more than one computer (though one worse than the other -- Win 7 unit with 12GB ram better than Vista unit with 8GB ram).


[QUOTE] ..how can you tell they're corrupt? [Unquote]
Viewing the downloaded photos on a web page is often the first clue, such as when I read a post on this site and the photos submitted by another member are corrupt. Or if I click a given link to Flickr or Photobucket and see a corrupt image or get message that image cannot be displayed as may be corrupt!

Also, photos that are downloaded from any site and saved by right clicking to the computer are often not viewable or exhibit corrupted images in Photoshop Elements, Lightroom, Windows Media viewer, Paint Shop Pro, or other image viewers. No question the image is corrupt in actuality, not just appearing so on a web page display.

As mentioned earlier, I have used Forefox (mostly) and also Internet Explorer as browsers (results are the same). I have installed no additional plugins for "improving the user's experience" that they try to lure you into using (such as Bing or special toolbars, etc).

On my two main work related computers I essentially do not allow addin programs if possible. I believe Adobe Reader and the 'Flyer' must be loaded as they seem to be required by most web sites to function correctly. I browse this Canon site and the Strobist site on my main photo processing computer, but it is not a general purpose computer. And no one else has access to my work computers.

My third office computer is another year older and is used for general office support, not photo work(anymore). But it also exhibited the download problem in brief tests.

Wife has separate computer, and the laptop is never used for any of my work so there can not be any in-house contamination.

I doubt it's your internet connection, but it's worth ruling it out. The common thing seems to be zone alarm. Try disabling that for 10 minutes and see what happens.

I don't use any kind of firewall and I have no virus problems. NAT deals with most of the problems a firewall will prevent.