computer suddenly stopped playing AVI

Hi, new to the forum - excited it exists, because Ive had my camera for over 1 year and still cant figure it out. I took some videos (AVI) and transferred them to my computer (XP)- they played fine. Then got a new laptop (with Vista). I copied all the videos onto a DVD disc and transferred files to my new computer. Now they wont play - no error message, just show black screen. What happened?
Since then any new videos Ive recorded play fine on my laptop - UNTIL the day I installed NERO to my computer and again, any videos I downloaded since the NERO day, will not play.... Also, Ive tried using conversion software to burn all my AVI files to a DVD in MPG format, and it refuses to convert the files that wont play anymore.
What is happening? I dont want to lose the files as they are of my newborn!

My nasty, suspicious mind first suspect's Vista's "Digital Rights Management"; it saw the files were coming from a DVD and assumed you were pirating it. And it doesn't like the codec Nero uses to handle your AVI files.

Thanks JOn, so how do I try to fix this? I have since uninstalled Nero - but still same issue. How do I deal with the codec?

Since I avoid Vista like the plague, I can't say for sure, but does it have a "Rollback" or "Repair" capability stashed away somewhere?

divix has the codex to play avi

Jon wrote in post #5594469
Since I avoid Vista like the plague

Me too. I'm still a happy camper on XP.

OP? Wondering this problem is resolved.

If not, try VLC Player. It should have no trouble playing them.
For playing them on DVD player on TV, use Media coder (freeware).

I don't use vista, hates it when I tried it with a new laptop that it came with. Wipe it and xppro all the way for me. It flies now.

Let us know if you got it sorted.

Regards.
Vic