Tor blocked from accessing website

I am experiencing what seems to be strange behaviour.

Using Tor on the wireless laptop it is able to access to webpages no problem.

Using Tor on a separate PC which uses the same modem but with a cable, the browser is much more slow and I am blocked from accessing certain websites. Eg Google etc.

The PC is more than fast enough in it's own right and other browser behaviour is normal.

Is there any obvious reason why this might happen?

This is not because laptop/PC, this is because of different exit-nodes.

You've randomly got node with huge spam traffic and blacklisted IP. Try again.

I can't even access This page via Tor on the PC. I had to access it using a standard browser. Tried Tor again with Google etc and it still isn't opening pages like these at all I'm afraid.