Blue Screen

I've been getting this blue screen for a while and now want to know how to stop it because it keeps coming back. It doesn't come up at a specific time, it comes when I'm doing anything at any time. I thought it was my space, but I have over 20 gb free space left in my hard drive. The blue screen looks something like this:
[external image: Posted Image]
But, instead of the "An attempt was made to write to read-only memory" … It usually says "DRIVER_IRAL_NOT_LESS_OR_EQUAL".

And instead of "NDIS.SYS" it says "USBPORT.SYS" … I haven't checked the rest of the numbers.. I just found that blue screen image online because it has all the other things it tells me to do. I checked in the BIOs and can't find the caching or shadowing.

Any ideas on how to fix it?

Thanks for all the help!

Have a look here for good overall information about STOP messages.
http://aumha.org/win5/kbestop.htm

0x000000BE: ATTEMPTED_WRITE_TO_READONLY_MEMORY
(Click to consult the online Win XP Resource Kit article.)
A driver attempted to write to read-only memory. Commonly occurs after installing a faulty device driver, system service, or firmware. If a driver file is named in the error message, try to correct the problem by disabling, removing, or rolling back the driver.
Error Message May Be Displayed When Using a Xircom Rex 6000 with a USB Cradle {KB 299371} Win XP (Work around: Attach it to the PC Card instead of the USB port.)
How to Use Driver Verifier to Troubleshoot Windows Drivers {KB 244617} Win 2000, Win XP, Server 2003

If that information gets you going, good!
But if you continue to have problems with resolving your situation, please feel free to post those specific questions back here for further assistance.

Best Regards