Optiplex 755 with new SSD resets randomly

Hi,

In the company I work for there are dozens of Optiplex 755 desktops whose hdd we've upgraded to Intel SSD 540s of 120GB. Before that, usually there were HDDs that worked in raid mode. Ever since we upgraded, quite a few desktops started acting up - they've been rebooting randomly and after the reboot the ssd cannot be identified. When this happens, the computer needs to be shut down, because it won't boot into the OS and BIOS becomes inaccessible. It just freezes. If I do shut them dow manually and then turn them on again, they boot Windows normally and that's that.

I've upgraded the drivers and I've updated the bios to the latest version (A22). The computers run Windows 7 Professional.

(the CAPTCHA robot check is just terrible! It takes about 30 seconds for me to confirm that I'm not a robot and it expires after a few minutes, so I need to make sure that I don't start writing AFTER I check it. Really horrible!)