Problem with cinnecting to Internet

Hello,
I have Windows XP Proffessional and I use Verizon Yahoo Browser and for some time I haven't been able to connect to Internet through any other browser (Internet Explorer and Mozilla). I checked firewall settings and added both applications as exceptions, I also renewed IP config, but it didn't help.
Let me add that with Verizon Yahoo Browser it works perfectly and also my other computer connects wirelessly (in the same network) to Internet without any p
Any ideas??