Firefox froze immediately after.
MC
cannot cause Firefox to crash. It does not interact with the Firefox process in any way. It can crash itself, and maybe Windows Explorer (since it has a shell plugin) but it does not plug into Firefox, and memory space is protected on Windows (since forever), so MC cannot access the Firefox process, or scribble over its memory, even if it wanted to, without making a specific Firefox extension (which, they didn't). This makes me
strongly suspect you have deeper issues on that machine. If the issues are isolated to MC, then it might be something specific to MC. But,
as soon as you start to see general system stability issues, that points to one of three things:
1. The hardware is broken.
2. The OS or drivers are broken (which makes the hardware broken).
3. The machine is infected.
Download and install Prime95 and run it in Torture Test mode for at least a few passes (a good handful of hours):
http://www.mersenne.org/download/If
that crashes, locks up the machine, bluescreens, or anything else? Then your computer cannot do math properly, the RAM is not working, or something similarly dire. It should peg all cores of your PC, and be able to run indefinitely. When you hit cancel, and stop the test, it should shut down nicely, and the computer should come back to life. It DOES behave this way on a properly running Windows PC.
If it fails, I'd be suspicious of things in this order:
1. Bad (or badly inserted) RAM.
2. Bad Power Supply.
3. Bad drivers, OS, disk, or something similar that "feeds the OS data".
4. Malware.
5. Bad or failing motherboard.
6. Bad or failing CPU.
It is also probably worth running through the DirectX Diagnostics:
http://windows.microsoft.com/en-us/windows-vista/run-directx-diagnostic-toolNothing you've described seems GPU related at all, but you never know, and it is worth a check.
Assuming both of those come up clean, I'd do a thorough check for malware, and check my disks for trouble (including running the SFC scanner):
http://wiki.jriver.com/index.php/Troubleshooting_DisksYou also mentioned an OCZ disk. That gives me a bit of pause. There were WIDELY reported issues under Windows 7 and 8 with MANY of the OCZ SSDs. I don't know if that one is impacted, and I suspect they've finally kicked out somewhat working firmware versions. But make sure you have the latest firmware on that SSD. There's stuff about this in the Wiki article I linked above too. Back up the entire SSD first, though. Firmware updates on SSDs
sometimes nuke them. Hasn't happened to me personally yet, but it has been known to happen.
MC may be
triggering an underlying hardware, OS, or driver issue that you don't see otherwise, but that doesn't mean MC is buggy. It means it is exposing a bug in your computer that you otherwise didn't notice.
It is still possible that your problem is just MC related, and that the simultaneous Firefox crash was bad luck. But, that is very, very suspicious. Seems to me like a general system fault (not bad enough to cause a bluescreen, but bad enough to crash applications or hard-lock), which usually indicates hardware (or driver) issues.