Hi,
This just happened to me too. I tried powering down the router and DSL modem... that didn't help. What did help was this:
Start>Run>cmd>OK
At the command prompt type >ipconfig /flushdns
You might need to power down/up the router/modem at this point, but the end result is that
www.QRZ.com started working again.
Cheers,
Tom
WA0WHT