iMac crashes every time I connect to broadband?
i Have a iMac OS X version 10.6.8 It works absolutely fine normally, at home I use it connected to our BT home hub and extension... No problems. However I have now moved it to my office where I have a Plusnet router. My iPhone, iPad and Newer iMac all work fine off this connection. But as soon as I connect this iMac to the broadband it crashes... i.e the circle loading icon comes up and I can't open any programmes and end up having to manually turn it off and on. I've tried everything, like restarting, forgetting the network, disconnecting and reconnecting the router, I've been on the phone to Plusnet for hours to no avail, run two virus software scans (avast and Sophos) I've tried doing software update sect. It works fine when it's not connected but as soon as it does, it's game over!
IS there anything I can do to resolve this? All of my work is on this Mac so I need to use it!
iMac, Mac OS X (10.6.8)