Browser doesn't point!

Hi
I have a rather strange problem. When I "point" my browser (IE6) to certain sites I get the "cannot find server" message yet when I point to others everything loads OK. For example I cannot access msn.com or google but I can access VirtualDr (hence I am posting this message). IE is also loading very slowly which I thought might be due to one of the recent M$ updates but problem persists despite uninstalling it.
I am running XP Pro on ADSL connection with a home network. Everything was working just fine until 2 days ago. Anyone any ideas? Thanks as ever.:confused:

I was having this problem a few weeks ago and saw a thread that mentioned running Ad-Aware. I did that and have had no problems since. Mine would also connect to some sites and not others. But Ad-Aware fixed it.

I have tried Adaware and Spybot but problem persists although it is variable. Today everything is running normally which suggests (to me) that there may be something wrong with the ADSL connection? Does this make any sense?

I seem to have the same problem, MSNBC will not load, all others are fine. The problem only exists when I use MS IE6, the pages load normally in Mozilla. Reloaded IE6, no change.
Any suggestions are welcomed.

Problem is solved, reinstalled NetZero and surfing is back to normal, now I wish I could explain why?