Thumbnails constantly being rebuilt

I've put up with this issue for a long time but it's really starting to aggravate me lately. I have thumbnail view enabled in folder options but every couple of days or it seems daily as of late, all my thumnails revert back to generic icons - folder icons, videos, pictures etc. God only knows how many thousands of pictures and videos I have on my machine and having to rebuild them on this frequency is a major pita. It's not like I'm using disk cleanup to delete my thumbnails, it just happens for no reason. Any ideas?

I have the same problem windows vista,7 rebuild thumbnails(maybe don't rebuild,simply overflow cache, this leads to the reconstruction of cache thumbnails, becose the file thumbnails increase in mb) don't work for me,but if you try increase pagefile.sys, yuo cache support more thumbnails.
an alternative is try thumbsplus7(works very vell) but isn't free.
an option try edit regedit, delete *.avi,*.jpg if you only works with *.mp4
i hope useful for you.
note:sorry for me english,I do my best .
not enough but at least try