go to a dos window (start-->run--> "cmd"--> enter) and type "ipconfig /flushdns"
you could also try purging your browser cache... but the first thing I suggested should do the trick
by the way
hmmm .. looking at this:
http://www.dnsstuff.com/tools/lookup...s.co.uk&type=A
it seems whoever changed the DNS record has made an error somewhere along the line, my guess is that "ns2.blueboxtechnology.com" is the only nameserver responding to requests... but doesn't have the record, whereas "ns1.blueboxtechnology.com" probably is set up correctly but doesn't seem to be responding to requests