explorer.exe - Application Error

I am having a new issue on my PC. When I try to access the following programs:
· Windows Explorer
· My Computer
· My Network Places
· Control Panel

I get the following error message:

explorer.exe - Application Error:

The instruction at "0x1003d065" referenced memory at "0x00000000". The memory could not be written.

Click on OK to terminate the program.
Click on CANCEL to debug.
Clicking on either will cause ne desktop icons to go away for about 10 seconds, and then my screen refreshes, but I can not access those programs.

PC/OS Info:
Windows XP Professional Service Pack 2 (build 2600)
700 megahertz Intel Pentium III32 kilobyte primary memory cache256 kilobyte secondary memory cache
256 Megabytes Installed Memory
102.57 Gigabytes Hard Drive Free Space

Any suggestions?

Thanks!