I am using WMP11. Maybe it is modifying every file it touches, but I have never heard of that.
Here is what I do. I have a WD Passport external HD. I have all my music stored locally on my home PC. I copied all the files onto the Passport, and set the Music folders up as folder pairs. Then I copied them onto my work PC, and again, set up folder pairs. That way, any changes I make at work can be replicated onto the Passport, and later onto my home PC, and vice-versa. Simple, right?
I run a synchronization every few weeks, and it overwrites nearly every file that WMP11 played, thinking that it has changed. I can find no changes, and I cannot find any mention of WMP doing that.
I'm pretty sure that this is not a flaw in SyncToy, but in WMP, but I cannot find a way to fix it.
Thanks,
Owen