Several possibilities.
matthew2777 said:
Ive Been Expieriencing This For 5 Years Already On Two Different Computers...
Hey Matt, I've experienced this problem myself. There are about a half dozen possible causes, none of them good.
The least tragic case first:
If all the files that were lost are all files that haven't been moved or modified in years, the magnetic recording of the file may be fading away as the drive ages. The quickest "fix" is to simply "move" all the data to another partition temporarily, then moving it all back so that it's written fresh. But start planning on replacing your drive now if this is the case. And be SURE that your drive is "mechanically" fine and not at fault before attempting this, or you could loose everything. Try simply defragging your PC first to "freshen" much of the data with a more recent recording. But realizes your oldest stuff is unlikely to be moved/freshened in a defrag.
For me, the problem was over-heating. Naturally, if your PC crashes due to over-heating, you're likely to loose whatever you were working on. BUT, directory entires can get screwed up as well, so even files you haven't touched in years can be "lost" (literally, they're there, but FAT can't find them).
Even though this has been happening for years, you could have a bad drive. Sometimes old drives get the hiccups (for lack of a better term) and start writing data in spots were other data already exists, thus destroying the previous file. Doubly worse when the "hiccup" occurs while writing to the FAT.
A dying CPU can direct the drive to do "bad things". Ditto for a bad or failing MoBo.
Bad ram can trash a file even while you are working on it. You end up saving "nonsense" to your drive that can't be read back later.
And finally, Windows could be screwed up. Typically a bad driver. If this is a frequent problem, try updating your drivers and or Windows itself to a NEW hard drive.
Sometimes, the cause of the file loss was a one-time thing that happened long ago in one or a series of minor disruptions, but your only now discovering the havoc that was created long ago as you just happen across those old files you haven't touched in years.
Hope this helps.
PS: I forgot to ask, are these two PC's connected?