Weird stuff hapenning with Internet Explorer exceptions

[Zourous]

So my boss enters a new seemingly harmless IE exception via GP to the whole school. Soon after that exceptions are doing weird stuff. Our main intranet page seems to be working (http:\\ts01) but the staff can't get onto our helpdesk (http:\\ts01\helpdesk) and various other local sites are playing up too. I looked at one PC where the problem existed. I open up IE and attempt to go to the helpdesk and it doesn't work. I then go to the where the IE proxy settings are, do nothing and just click on ok and then go back and refresh my page and bingo everything is working again. Does anyone know what is going on here as I'm puzzled?