Outlook XP Instruction at 0x6601cd49

I am running Outlook XP (2002) on Windows 2000 Pro. If I leave Outlook open for a period of time, it tends to lock up when I send an email (receiving emails are not interrupted). The error message ? ?The instruction at “0x6601cd49” referenced memory at “0x000000a0”. The memory could not be “read”. Click OK to terminate the program.? – requires me to shut Outlook
down. Once I reopen it, – ?the archive folders did not close properly? – message appears and the program automatically initializes another program to fix it.

MS KB does not recognize this error message. Can anyone tell me what is
going on? And is there a fix?