Amazing Internet behaviour on Win2000

I know this sounds something funny or fishy, but i am encountering a strange behaviour on my win2000 machine. The trouble is that i can browse web sites like mail.yahoo.com or monster.ca etc…from my win98 or winxp machines, but i cannot browse it from my win2000 running from my same machine (in a dual boot config).. I can browse other web sites from win2k machine.. I tried deleting my cookies and offline file contents from win2k, but of no help. I ran Norton antivirus also, but it gives the same behaviour.. Can somebody help me pls…