Internet Explorer on my test Windows Server 2003 box has been playing up for a couple of days - every time I clicked a link which opened a new window, I got a blank window with nothing in the address bar. Annoying, but sometimes you don't have time to sort it out, so you end up working around the problem. For example, I have been copying shortcuts and pasting it in to the blank window. However, there's certain links which just don't work doing this, such as those with scripted links.
There's a limit to my patience, but the answer took no more than two minutes to find and resolve without resorting to reinstalling. From the Microsoft knowledge base under article 281679 - I just had to follow the first step, (re-)registering urlmon.dll. I still don't know why this happened in the first place, but there you go.
The article above has lots of other information if the first step doesn't fix it for you, and applies to IE5, 5.01, 5.5 and 6.0