cannot connect to websites

Hi,wondering if anyone can help,I suddenly can't get onto certain websites,the main one being myspace.Everything has been fine until the last couple of days when my pc has been running quite slowly on the net.I scanned with spybot,windows defender and AVG today and spybot picked up on a trojan which it said it fixed,since then my pc seems to be running quicker but also since then I haven't been able to get on a couple of websites the aforementioned one being the one of them I use the most.I get "The connection has timed out" everytime I try,the little bar at the bottom doesn't even begin to load up I am running on windows xp on a dial-up connection.I had a similar problem to this once before and couldn't get onto Amazon,I couldn't find anyone who could help.I was eventually able to get back onto Amazon about seven months after the problem first started but still have no idea what happened.I'm quite perplexed If anyone could give me any help I'd be most grateful.
thankyou
Lain