I have certain times when I can surf the net at work as well, but I've never been questioned and we have some serious filters going on. They even block Google Images and sites such as NFL and Yahoo Sports for some reason, BUT I can get to all my music sites and ebay
One thing My co-workers and I have done over and over in the past was to go to your Control Panel and into Internet Options and then Delete Cookies, Delete Temporary Internet Files and then at the bottom, Delete Browse History
EVERYTIME we log off the computer. I started doing this 6 years ago when I started there, and some of my co-workers questioned what I was doing, so I showed them. It caught on like crazy and now damn near everyone does it. Cover Your Ass!!!

See if you're able to access the control panel at work and see if you can do all this WOF. Good Luck
