Unable to stay connected to Internet

Hi,
I have an unusual problem. When I connect to AOL through my network at work(lan line)I do connect to AOL but after approx. 1 min. I get disconnected. Then right after that when I try to browse the internet using Internet Explorer. I’m unable to. But when I close out the I.E. and open it back up I can browse the internet. I tried re-loading AOL from scratch. Still not working. Aol in the past workied fine. I have had no problems. I did a virus scan, spyware scan. All seems okay. Not sure whats happening. Any help would be appreciated