Forum/Catagory > Blank Page?

[Matthewd5]

Ok, I'm using IE the newest version.
I use it both here at work and at home.
At home I can make a catagory just fine, without any problems.
Yet here at work, when I switch the box from forum to catagory, it goes to a "Internet Explorer Cannot Display This Page" screen.
When I f5 the page, it goes back to forum.
I just can't get it switched to catagory.
I also have that display page pop up whenever I'm doing other stuff aswell, like editing forums and catagories, but when I f5 then, it works.

Help needed :S

Thanks in advance!