Strange networking problem

Hi, My router is working fine and my broadband connection seems okay. Problem is this. If I use firefox, getting pages can be hideously slow. Trying to do an svn checkout is painful from a terminal window and I am getting resolution problems when trying to do a yum update (run out of mirrors error). If I try to ping I am getting 100% loss, yet emails can come and go without a problem! Has any ideas what on earth is going on? I'm using rawhide on a box last updated 2 days ago. TTFN Paul -- "Some people will do anything for a woman in uniform" - The Doctor - Unregenerate (Big Finish audio)