I have only 1 user that I can tell right now that every so many days keeps getting the following error message when in public folders:
Cannot expand the folder. Your server administrator has limited the number of items you can open simultaneously..
Now if she reboots all seems to be fine again for a few days. There is a setting on the exchange server that we bumped up from the default of 250 to 2000 but she stile seems to have the issue from time to time.