Backup software keeps re-copying files OSX

I've tried 2 backup programs (Silverkeeper + Filesync) on my wife's Snow Leopard. They both copy her 30 gigabytes of pictures and movies to the external drive. Then, without me opening any folder whatsoever on her computer, they recopy the same files again the next time I run the backup (which today- as a test - was seconds after they finished).
Could her AV be writing to the files making the software think they've been modified?
Any help is appreciated!

 

Once an AV (an offline AV scanner in my case) did in fact cause just such a thing to happen - see https://www.wilderssecurity.com/showthread.php?t=308960.

 

Thanks MrBrian.
I really get a feeling that's it.
At some point when I feel like sitting through 2 hours of copying, I'll disable her AV and test again.
What did you end up doing?

 

You're welcome .

I posted about it in the AV's forum, and stopped using that AV rescue disc scanner. I don't know if it was ever fixed.

 

Good advice. That's exactly what I'll do if it is her AV. It will be off her computer!
Backup is too important.

 

Well, her AV was the problem. I disabled it and the backup was over in seconds.
I really appreciate your input MrBrian, because it pushed me to research it.

 

Glad you found it .