hi I have a large network using exchange server 2003, recently one of my users switched his outlook acount to cached mode, however when he switched back to using the exchange server to store and retrive his emails, he get an error, unable to open your default email- folders what could be wrong help

I don't know what you mean by "cached mode," but it's obvious that whatever Personal Folder is listed as the Mail Delivery location is not where it's supposed to be. Soylent Green is PEOPLE!!!

Changing the default to casched mode should not have affected the folders readability. Cached mode is mostly for people who are traveling and using slow connections like a 56k modem. Cached mode allows a small amount of the email to be downloaded (usually the subject line) so you can see what e-mails you have without having to wait for ages for the whole e-mail to download. So you see that cached mode should have nothing to do with reading folders. Make sure the client didn't change the exchange servers name or address. If all is well there, try disconnecting from the folder and then re-map to it.