memory errors

We are seeing an increasing number of memory errors such as “The instruction at ‘0x77fc9d7b’ referenced memory at ‘9x943a9650’. The memory could not be ‘written’. Click OK to terminate the program.” This particular message came from Autocad 2000. We are running half and half with windows 2000 sp2 and nt workstation sp6. This user had autocad 2000 and outlook 2000 sr1/sp2 open. Does anyone have any ideas on how to avoid these errors? Thanks!