Hopefully it means "The driver for one of your devices is corrupted and should be updated/reinstalled".
It can also mean "This device is failing and must be replaced".

Given that I haven't put any new drivers on my machine in the past couple weeks, and that we already know something on my computer is shot, I'm thinking it means the latter.

Oh well. Already knew that.

Short explanation: There should be a driver file name in the blue screen, which identifies the driver that is at fault (it will often end in ".sys"). This typically means that the driver was badly written. Google the driver, and figure out which device it belongs to. Then go to the vendor's webpage and check for an update to the device driver. If it's that bad, hopefully you're just running on an older version and they've already fixed the problem.

Long explanation: The most common reason for encountering DRIVER_IRQL_NOT_LESS_OR_EQUAL is that the driver tried to access memory that was paged out while processing an interrupt. Since while processing an interrupt, the driver is running at such a priority level that it even defeats paging requests, doing so would result in the driver not getting the information it was asking for. Since there's almost nothing good to be done at that point - for all the kernel knows, processing that interrupt correctly could be critical to the operation of the system - the kernel proactively takes itself down to protect the machine.

I'm not sure I can think of a case where this is not because the driver at fault was written incorrectly. This can pop up suddenly when the memory footprint on the system changes in any way, typically when more pressure is placed on it. Making an assumption that Photoshop is a memory heavy application, for instance, if you suddenly started running Photoshop on such a system, all of a sudden the memory system is under heavier pressure, it pages out a page belonging to the driver, the driver gets called to process an interrupt, and wham, your system goes down. I think you mentioned this happens under heavier stress - that's why.

Note: Actually, this is probably one of the best possible stop codes you could be running into, all things considered. It doesn't mean your system is trashed - it's just the code that's providing communication between the operating system and the machine isn't well written. This is a common stop code, it's very easy to prove the driver is at fault, and it's also relatively easy to diagnose and fix.

Thank you for the explanation. (You know, if I can understand Magic: the Gathering rules for the stack, I should be able to understand computer processing at the machine level. But I have yet to encounter a handily downloadable document that explains the latter...)

Hmm. The only driver I was trying to update lately was the NVIDIA GeForce driver, which I really hope is not at fault, since apparently the most recent driver version doesn't support my chipset (even though it says it does, when I tried to install it it detected no compatible hardware...)

Oh well. If just playing music while writing is enough to crash the system, I know I'll encounter it again. Hopefully I can track down the responsible driver and repair it. I trust myself to do THAT much at least, if it's possible for me to do so. (Or I trust myself NOT to delete the motherboard drivers again at least.)

Incidentally, any chance this could also be the source of my previous kernal fault?

Go Wikipedia? This is a description of the virtual memory part of the explanation. (The bits that discussed paging and memory not being there.)

If you mean what was causing your computer to reboot randomly, yes, this could very well be the cause. This blue screen would have resulted in the system abruptly rebooting. Of course, if there's something I missed in this saga, let me know and I can try to dig into it/explain.