Internet won't connect to some webpages

Hi guys

Recently I have seen a problem developing on my desktop pc regarding the internet. I use an online aution with live video feeds and audio, When I connect to this system I get a performance check which has started coming back with the errors because my download speed is only 42kb I have checked with my provider and they say I should be getting 1700 - 2000 at my router, This is a minor niggle though. Something else has decided to rear it's head today. I have bought something from ebay and as normal went to pay for it straight away using paypal, clicked on pay now and then nothing but a blank screen and the loading symbol.
I left this for ten minutes still nothing
I refreshed still nothing
I deleted cookies etc still nothing

So i went directly to paypal to try to log in as soon as I click the link to log in same problem!!! it's really got me baffled any help would be appreciated

I run
Windows XP SP3
Internet expolorer 7
Spyware terminator
AVG 8.0

I have also followed all the spyware removal / cleaning requirement on this site I can post the logs if required, but i'm leaning more to a security setting slightly wrong.

Any help would be greatly appreciated

Many Thanks