iTunes songs cut off early

Heyas;

So I have been going through my iTunes collection - backing up and getting missing artwork, etc. and I have noticed that several songs end early/get cut-off. This happened to one song a while back that was a download from the iTunes store. I figured the file somehow got corrupted so re-bought the song from the iTunes store. Now that it has happened to several songs I am suspicious that there must be another issue than one corrupt file.

The files that cut off early are AAC format. There may be some older MP3 formatted songs that are effected as well but I have not found any as of yet. The recently effected files are ones I imported from my CD collection; but as mentioned above, I have had issues with iTunes store songs as well.

I also recently deleted all the songs from my Windows 7 PC and transferred all the files from my Mac Mini (where I keep the 'master' copies), using 'home sharing'.

Thanks for taking the time to read this post

Any suggestions?

I use a Mac Mini 10.4 and a Windows 7 PC. I keep both iTunes libraries synced up.