Tf2 won't start. Every time I try, it insists on validating the file cache. Whenever I validate the file cache on tf2, it always stops at 100% and won't actually complete. So every time I try to start, it keeps doing that and the game itself will not run.

Based on my googling I have tried:
*Defragmenting the file cache(worked for a while, but doesn't anymore. It just immediately jumps to a full bar and doesn't list the total clusters or anything. 1/ )
*Defragging the entire hard drive (again, worked for a while but now it doesn't)
*Deleting/renaming clientregistry.blob (didn't work)
*Renaming the tf2 folder and doing a fresh reinstall (worked for all of one night, and verification would still halt at 100%)
*Did a disk check to see if anything was wrong with my hard drive, including scanning for and attempting recovery of bad sectors. (nope)
*Completely reinstall Steam as well as ALL of my games, AND move Tf2 to my SSD since fragmentation doesn't mean dick on SSDs (again, worked for all of one night)

I'm at wit's end. The only thing I've done that seems to make it start is play TFC for a little bit. Probably a coincidence and I just have to wait a few minutes... or maybe it just gets jealous and decides to run for me. (I did play half life source for a little bit the other day but that didn't fix it... TFC did. So that's creepy. Then again, I didn't play hl:s for as long as TFC.)

Anyone have any idea what the hell ass balls is going on? Google has failed me.