Graystar wrote in post #2879526
I work with computers for a living and I must say...I've never heard of a file being read from a USB device where the computer failed to signal a problem, but the file was corrupt. For this to happen requires a hardware failure.
A flash card operates just like a hard drive. The interface protocols of storage devices are very mature, and error detection and even error correction is performed during transfers. But at the very least, the OS will signal a transfer problem and stop the process. There has to be something very wrong with the hardware in order for this process to fail.
Unfortunately, that's actually far more common that many people realize. I've seen many problems that were initially blamed on Windows but turned out to be bad hardware. And I've seen disk transfer issues that were caused by bad interface cards or bugs in the computer's BIOS. But when you have good quality hardware these processes work properly and reliably.
Knowing this, I've always bought top quality hardware for myself. I'm a computer programmer so I depend on my computers for my livelihood. In years of doing this I've never produced a coaster in my CD burner, and I've never had a problem reading a USB device.
I would recommend replacing any device that didn’t signal a transfer failure when one occurred. The device is faulty.
For the record, I'm also a computer professional, with years of hardware experience, having been working with PCs since the beginning.
OP is transferring directly from the camera to the computer. So it's effectively going over a network, not a local hard drive. Plenty of room for corruption there. There's also plenty of anecdotal evidence here of people discovering their card readers or cables were bad only when they saw the corupted pictures on the PC, while still having the good ones on the camera.
I've been dealing with computers long enough to know that you don't delete the original until you've got several backups because sooner or later you'll get bit. My files stay on the card after I've transferreed them to the initial computer, where they're indexed. They're then transferred to the principal computer, where they reside on two separate external drives, one ordered by camera and flolder and the other by subject. They're then backed up to two DVDs, with overlap between sessions, so each file is on at least 4 in total. They're also backed up to two more external drives. Only then will I consider deleting the original card files and the files from the initial computer, but not until I need the additional space. Deleting before you've made any backup is begging for trouble.