Enabling AHCI fixed 0x0000007B BSOD on old Windows 7 partition - but now it restarts whenever I select shutdown

I built a PC that's been working for a while (aside: mainly using a non-Windows OS, which seemed to start kernel panicing more frequently). It stopped booting in any OS from the partitions on the SSD (giving BSOD 'STOP: 0x0000007B (0x80786A58, 0xC0000034, 0x00000000, 0x00000000)').

I installed Windows 7 on a separate drive and magicandre1981 kindly explained how to make the old SSD partition work by switching to AHCI mode in BIOS (and make the new HD partition work by enabling AHCI).

However since this whenever I select shutdown in either Win 7 partition, the machine restarts instead (it shuts down in 1 out of 10 attempts). This happens even when I explicitly log out and then shut down from the logon screen, and even with all cables bar power & monitor unplugged. This SU question suggests updating to BIOS, but I'm not sure other OSes I want to reinstall/reenable will work after this. I'm no BIOS expert, but have changed a few relevant-seeming settings, and mine look much like the bottom half of these ones.

My first suggestion would be to update your BIOS, following the manual for your specific motherboard. I had a similar issue with booting my new build that was due to a BIOS issue with my particular SATA drive. I would also update the drivers for all of your devices.

I have several other suggestions for you, but this site has just about all of the ones I could think of and provides guides to help you through many of them as well (including updating drivers), so I would suggest going through these and seeing what you can come up with.

http://pcsupport.about.com/od/findbyerrormessage/a/stop0x0000007b.htm