Hello and welcome to the forums.
Double check with whoever is administering the Exchange server and make sure your POP3 port setting on your end are set properly he may be using/requiring an SSL configuration something like 995 instead of 110.
Wow, I hope they're paying you well. Generally you would double check the settings on both ends, at the exchange server compare the problem account with one that you have confirmed to be working in both directions. Then on another client machine that Outlook is known to be working on, check all the account settings and compare them.
Here's a link with a walk through that might help How Do I Manually Connect Microsoft Outlook 2003/2007 to my Microsoft Exchange 2003/2007/2010 Server?
although I noted that he recommends checking the box for "Use Cached Exchange Mode in step #4, while others have reported that unchecking the box resolved problem that they were having. That's another reason why I suggest comparing settings between a known good account and the problem account to determine if there are any discrepancies.