required data was not placed into memory

On startup, I get this error message:

"The instruction at 0x77d49dda referenced memory at 0x01733328. The required data was not placed into memory because of an I/O error status of 0x0000102"

I can't access the taskbar or Start button while this message is up there, so the computer is pretty much useless, 'though I can access prog's and stuff on the desktop.
Thanks for reading!