I have a win2k3 file server with about 30 users using Winxp in one of our sites. Each server works independently on its own network/subnet mask. In addition we have a managed firewall and we have a web filter. About 3 weeks ago my server stopped going out into the WAN. If I try and open IE and go out on the web it times out. If I try and ping any website it times out. I did not have this issue before. I checked my DNS and that has not changed. The funny thing is when I put an alternate DNS of 188.8.131.52 I am able to go the internet through a normal browser and through a command line. In fact my web filter came up and I had to authenticate in order to go out on the web. When I take the alternate DNS off, bingo back to square A and cannot get online. I am however, am able to ping the router and any other servers on the network/subnet and even remotely log onto any other server via remote admin whether I have the alternate DNS or not.
Any suggestions as to why this may be happening?