Emails just started hangin in outbox

This is really really wierd and this is getting to the point where i can't sleep anymore at night (well not that bad but it's pretty bad).

I am a technician at a company that i work for. We have exchange 5.5 and Internet Pop3 Accounts for all of our users (don't ask - i know what your going to say).. anyway.. we have our email combined so that we can use internet email and internal email together at one time (Our network administrator is insistant on seperating out emails so every user has to go out of there mail get back into it and go out and get back in if they want to switch between internal and external, is it me or is that the craziest thing that anybody has ever heard of - you have to understand our network admin **No Technology bad! move backwards instead of forward **** ) anyway.. everything has been going great until last week.. Everybody's External emails were getting stuck in the outbox.. I mean this wasn't just on a couple of pc's we are talking the whole agency. Our network admin said it has to be the outlook client (office 2000).. i would agree with him if it was just a couple of pc's that was doing this but it's the whole agency. We have just gotten all new cisco equipment recently to but right when we got it we were still able to get external email to go out just fine. We have tried disabling smtp on the pix firewall and that didnt' work.. we tried rebooting our main sever to see if something just go hung up but this is really really wierd.. The only fix that we have found for this is to upgrade to either office xp or office 2003! STrange! any suggestions from anybody?