Compounding upon Pow's advice, an IRQL_NOT_LESS_OR_EQUAL can also be caused by a lot of unnecessary processes creating conflicts. I'm assuming you are using Windows XP as I write this. First of all, don't throw away a HDD if you can fix the problem on the software side.
On Windows XP, do the following steps...
1. Click Start --> Run. Type in "MSCONFIG".
2. When the MSCONFIG window loads, choose the "Startup" tab.
3. Click "Disable All". Select "Apply", then "OK".
4. After MSCONFIG is closed, restart your system. Upon your new XP boot, you will get a window telling you that you made changes to your system. Dismiss the window(there should be a checkbox for "Don't tell me this again"), and close it.
5. If prompted for a second restart, go for it.
What this does is disable all services, and upon boot, XP will automatically re-enable the services your system requires versus the ones you don't. If you don't get the IRQL_NOT_LESS_OR_EQUAL again, then there you go. Problem solved.

Also, if you're using a laptop, and the abovementioned doesn't fix it, clean the cooling turbines
carefully. Portable PCs are more prone to overheat damage(my laptop has a P4 HyperThreaded running at 2788 Mhz that used to run really hot), the cleaner they are, the better and longer they work. In either heavy 3D apps in XP or lots of processes on Linux, doesn't exceed 50C. Good luck.

EDIT: I forgot to mention I had this on a recent install of a free AV/Anti-Malware program. If you're running one, you should see if the abovementioned method fixes your problem. If it does, well...might want to ditch the "free" "anti" virus.