Referenced memory error

I wonder if someone can help me with this problem. OS is Windows 2000. Users are getting the following error:

The instruction at 0x71739dfc referenced memory at 0x088dfde4. The memory cannot be read.

Tried looking for virus/worms, updated with critical updates, but users are still getting this error. There is another error that I will post also, but not on this discussion.

Thank you in advance for your help.