Entourage email problem


(I posted a problem earlier regarding this but the problem has changed a little bit... (in that Entourage is now retaining the password that's been put in the keychain, it's just not recognizing it) and i'm hoping this explanation is a little clearer).

I'm having a problem with my email account that is in Entourage and comes from an exchange server. Some work was done on the server at work, and the IT guy at work and I both belive that my problem is due to that because the he had a breakthrough and solved his problem at the exact same time (thursday morning) that i started having this issue. The thing is, he doesn't really know anything about Macs and I bought mine knowing that so I'm sort of on my own to find a fix for this issue.

Basically, Entourage won't send or receive email on the account that I use at work that comes through an exchange server. It prompts me for the username and password, but rejects what i give it saying that either the username/password or security settings are wrong. I know that the username and password are right because they are right because I can get to my account via webmail. The security settings are the same as they always were - and i've gone over them w/ the IT guy at work. Everyone else at work is on a PC and running fine through Outlook, so he says that it is probably something due to the fact that the mac uses certificates, and the PC's don't. He says he suspects that this is a common problem and that Microsoft will come up with an update for it soon. I am checking daily for an update. In the meantime (and in case that isn't the problem and an update never appears that fixes this) does anyone else have any ideas? I have already tried resetting the keychain a couple times. that made it retain the password in the Accounts section but it still asks me to login to check email (just for this account, not my road runner or gmail accounts - those are fine) and then says i have something incorrect. Please let me know if any of this is unclear, and thanks very much for reading.
elsa, I have two suggestions for you. First, make sure that you have updated Entourage 2004 to the latest version. If you don't already have the latest version, see if the latest works after you upgrade. I am on record with my contention that Entourage 2004 is a steaming pile. But, it seems that you have to use it. When Entourage gets out of sorts, my remedy is to create a new account within the app that accesses your account on your server. Everything that you placed on the server will still be there. Hopefully, the new Entourage account will be able to access it. Word to the Wise: After you regain access to your Exchange account, please allow only default Entourage settings to access it.