Have you tried resetting the Share(s)?

Below is a more in-depth explanation about the Net Folder feature,
How to use it, and What problems may occur.
http://www.slipstick.com/outlook/netfolders.htm

Outlook uses forms for everything. Perhaps a refreshing of the
forms cache might do the trick.

To do so, follow these steps: 1. On the Tools menu, click Options.
2. Click the Other tab, and then click Advanced Options.
3. Click Custom Forms.
4. Click Manage Forms.
5. Click Clear Cache.
6. Close all open windows, and then restart Outlook.

If the above does not work, try the following.

Deleting the Forms Cache File

The Frmcache.dat file is the primary file to delete. The Frmcache.dat
file serves as an index of the individual forms that have been cached
on the computer. Use the following steps to manually delete the
Frmcache.dat file. In addition, these steps delete all of the cached
forms on your computer, which are stored in subfolders of the
Forms folder.

1.. Quit Outlook.
2.. Search the Hard drive (F3) to locate the Frmcache.dat file.
(Be sure to check in HIDDEN files on W2K or WXP.)
3.. Delete all that are found from the FIND window.
4.. Open Outlook.

When you restart Outlook, and use a custom form, the forms cache
is re-created. Until a custom form is used, Outlook does not re-create
the Frmcache.dat file.

Nikki

"Mike Bag" Mike wrote in message
...
I was sharing a calender from another computer for some time with no
problem.
One day it stopped working. I have tried reinstaling and used all of the
help
procedures I could find.Still nothing works and I continue to receive the
same message " Can not accept net folder invitation". I know I am probably
just missing something real simple, can this be a firewall or network
issue?
Any Ideas ???