Outlook FLDPUB.dll

I have this error message in Outlook 2000:

“Outlook has caused an invalide page fault in module fldpub.dll”

We are 10 computers with an outlook network without Ms-Exchange. We are using a postoffice and we are sharing each calendar to everybody. I am having this error on some of the computers. I have executed the file “NFCLEAN.EXE” (Net Folder Clean) to solve this problem and I have to do all the sharing again on each computer. After 3 or 4 weeks the problem comes back. Please Help me!!!!