cannot make http, https or ftp connection

hi guys

first time posting here hopefully you can help me out. My desktop recently stopped being able to connect to the internet and i'm trying to work out why as i have changed my set up at all.

Basically I'm running windows xp on a dell optiplex gx270 dhp. our internet comes down a broadband connection to our router (i think its a 2 wire gateway??) provided by BT. we then use that to form a LAN which i pick up on my macbook wirelessly and share across to the pc using its built in internet sharing via an ethernet cable. hope that makes sense - can't say i'm great with computers.

anyway this set up was working fine for about 2 weeks and has now stopped. my laptop and all the other computers in the house (which are also macs) are still connecting to the internet fine and have no problems. I've tried scanning for any viruses using the anti-virus software i have on the pc (F-secure for workstations) which came up with 2 spywares that i cleaned up but that didn't help. I've tried turning it off and on again, unplugging the ethernet and plugging it back in a couple of minutes later, turning the firewall off. I've tried to use the network wizard to set up a new network or connection which i don't think i did properly (didn't work and couldn't see any new connections) and tried installing a winsock patch but that didn't work either.

In the network connections section of control panel it's showing my LAN as connected but when i tried pinging websites it sent 4 packets and recieved 0.

according to ipconfig/all its ip routing isn't enabled but Dhcp is and autoconfiguration is. not sure what that means but hope it helps.

sorry for long post but as you can see i'm at a bit of a loose end. i don't really understand pc's having always used macs and only really use the desktop for programs which are incompatible and playing games (the later at the moment as i' home from uni) but it won't launch any of them until it can connect to the internet for steam (seperate issue with that which i'll sort out once it can connect to the internet through a browser).

any help much appreciated but please explain it to a pc illiterate person - cheers!

 

sorry guys - just tried hard wiring it into the router and it worked fine so looks like the problem is with my laptop sharing the internet. sorry for wasting your time