CGminer and GUIMiner make computer disconnect from internet.

[Blowmybarrel]

I have been mining since Christmas and come across this problem a few times but not enough to bother me until now.

More times than not if I stop mining and try to restart later I can’t. As soon as start to mine the internet goes down. Once it’s running it is fine but I just can’t get it started sometimes
I have tried both cgminer and guiminer and as soon as I stop trying to mine the computer reconnects.

The card is overclocked and setting it back to its factory setting makes no difference.

Does anyone have any idea what could be wrong?

Thanks,

Blow