Windows 7: SSD Drice suddenly disappeared from BIOS and won't boot.

Hi,

I was installing a SSD for a friend, I've done a few using Pargon migrate successfully. In fact the only time previously I've had a problem was with a fresh install on a SSD. Probably the opposite of most people.

Anyway all went well. ACHI mode was enabled by default in the BIOS. I'd used this SSD previously for a few weeks in another laptop and it seemed fine. I was shipped with the latest firmware from Kingston. It's a cheap Kingston V200. Seemed fine in the other laptop and seemed fine in this one for 24 hrs. I checked TRIM was enabled, disabled indexing, defrag and readyboost. I also updated the laptop's BIOS.



So seeing as I'd have the laptop for a wee while I thought I'd run some AV and antimalware scans. Remove some old software and tidy it up a bit. Everything had been going smoothly but while running "comodo cleaning essentials" the laptop froze. I gave it a good 30 mins before forcing it off by holding the power button. Upon reboot it said that it couldn't detect a boot device. I checked the BIOS and suddenly it's not seeing this SSD anymore. I removed the SSD and put it in a dock and when I connected via USB it to another computer it said it needed to run check disk, so I let it. And it seems OK, the files are there and accessible. Put it back in the laptop and it's still not seeing it at all. Put the old HDD in the laptop and it boots fine.

This really has me stumped. And it had to happen at 1am. lol I've spent the last hour and a half googling with no success. Anyone know what's going on?

EDIT: I connected the SSD to another laptop and it is picked up in the BIOS. I'm going to try re-flashing the BIOS on the ASUS.
EDIT2:
Switched to IDE mode from AHCI, exited BIOS, saved, reboot, back in to the BIOS and the SSD was detected, switched back to AHCI and it boots.