That is strange, the event viewer on the problem PC may give some more information.
1. Click Start
2. Type eventvwr.exe
3. Press enter
4. Search through the groups for errors and warnings.
5. Double click on each error and or warning.
6. Locate the copy to clipboard button,
(under the two arrows)
7. Let us know what you find. (paste the results)
However there may be a problem with the exchange server.