outlook 2003 refreshes every few seconds

Yesterday one of my clients complained that his Inbox seemed to be flickering. When I looked at it it seemed that it was refreshing evry 10 seconds or so. This morning another client on the same network said that she was having the same problem and then 30 IE windows poped up and as she closed all of them, the last 18 or so just closed. I am suspecting a virus but my anti virus and firewall are up to date and have not detected any threat and I have not been able to find anything on the web to help me identify this as a specific virus so that I download a removal tool. Any help would be apreciated.