About 2 hours ago, my PC froze for no apparent reason. I couldn't get into the Task Manager, so I had to hit the Reset button... and that's when I came across an old "friend" of mine:
"Disk I/O Error
Replace the disk and then hit a key"
I've had this error with two OCZ Vertex3 SSDs in a row, which is why I switched to a Crucial m4 128GB. It ran fine now for about 8 months, without any problem... until today. With each reboot, I now get this error message, even though Windows boots normally afterwards... only to lock up again within half an hour or so.
After reading this thread, I installed CrystalDiskInfo to check the drive status and indeed: Power On Hours is at 5211 hours now... I bought this computer (and thus the SSD) back in November 2011, and had it running 24/7 more or less.