[X-Newbies] Dang Comcast!!!

[J]

Dang Comcast was in my parents home because they went with them for  
their phone service.
The technician messed with their computer when he changed the modem,  
supposedly having something to do with configuring their phone.
I thought the worst damage he did was simply change the homepage.
But now, internet sharing won't work. It says I am connected to their  
network, internet sharing is on, but I can't get on AIM or the web or  
email.

I can still connect to my brother's network next door, on his Netgear  
router, as this is how I am writing this.

DANG COMCAST...what could they have done to the computer????