Internet Explorer (IE) has a number of documented problems where certain parts of the browser -- or the browser as a whole -- simply stop working.
You click on links and they no longer work. Type a URL in the Start | Run dialog and it doesn't bring up an IE window. These are just two examples of the numerous problems users encounter.
One common way people deal with these problems is by simply reinstalling IE. While this usually does do the trick, you might consider reinstalling IE total overkill for a problem that is relatively simple.
Most of these types of problems with IE are due to many of IE's support DLLs (browseui.dll, urlmon.dll, iesetup.dll, for instance) becoming unregistered. Sometimes this happens maliciously: a piece of spyware, for instance, might unregister such DLLs as a way to hijack parts of IE's functionality. Other times it happens by accident.
Whatever the cause, the solution is to re-register the DLLs, either by hand through the REGSVR32 command or by reinstalling IE. Reinstalling IE fixes these problems because all of the associated DLLs are re-registered by the application installer, but re-registering by hand is generally less of a hassle than running a full install.
I have written about these problems in the past, but listed only manual fixes. Microsoft has since taken note of this problem and introduced a not-very-widely documented change in Windows XP Service Pack 2's version of IE that allows all of IE's DLLs to be re-registered at once. From any command prompt, type:
"%ProgramFiles%Internet Exploreriexplore.exe" /rereg
Please make special note of the quotes, which are required to delineate the pathname for the executable.
This trick will not work on any other version of Windows; it is exclusive to Windows XP Service Pack 2.
(Thanks to the excellent folks at JSI.com for the technical details of this tip.)
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter. Check out his Windows 2000 blog for his latest advice and musings on the world of Windows network administrators -- please share your thoughts as well!