internet disconnects of 30 seconds

Hi techies,

i have two computer problems and will be greatful for your help.

1.Am using windows xp and dial-up internet connection.its was working fine until recently.its only allowing me to connect to the internet for 30 seconds, then drops the connection and i am able to reconnect for only 30 seconds.Am i infected with a virus?. what can I do to solve this problem.

2. I have a friend using wind xp and ADSL internet connection, I am able to connect to the internet but cannot open internet explorer its just not opening when I double click it.Can it be a virus any recommendation and removal tools

thanks