I have strange effects with my Windows 7 PC. Sometimes the system hangs up with permanent lightning of the hdd led. After a few minutes the system stops in an undefined state (no blue screen). Then the only way is to push the reset button. After doing this the bios doesn't find the boot ssd. The only way is then to cut the system from the power an wait a few minutes.
I had these problmes first with an X25-M G2 80GB SSD, the I tried an SSD from Extrememory and know the same problems with a brand new Intel D320 120 GB SSD.