Can't open the internet

[Wossi]

My sister is having problems loading up the net when using both firefox and IE. She can get on msn and skype no problems but no actual web pages. Any ideas on how to fix this as I have no clue.

Thanks.

 

[Wossi]

She's connecting using wireless same as the laptop I'm currently using, but when she clicks on firefox it comes up with page loading and that's it, it never actually loads. Every other machine in the house can connect apart from her laptop.

ISP is Virgin.

 

[Wossi]

Finally got it sorted late last night. She had tried downloading winrar and clicked on the dodgy version that has a virus It was changing permissions so nothing could be changed. The damn thing installed a copy of it's own explorer into the system32 folder which was messing everything up.