Microsoft website causes pc to freeze

I recently installed a new wireless network and ever since have had a problem with internet explorer. Every time I access Messenger or any Microsoft website the whole computer freezes and not even task manager is accessible - I have to do a hard reboot.

I have checked the hard disk, run a full Norton system scan and even reset Internet Explorer settings. The troubleshooter in Messenger says all is fine.

Any Ideas? As I have now run out!