On June 10, 2010, security researcher Tavis Ormandy publicly disclosed a vulnerability in the Windows Help and Support Center service in Windows XP and Windows Server 2003. This vulnerability would allow a remote hacker or exploit hosted on a web site to cause commands to be executed on a vulnerable computer. The way this disclosure was released has met with numerous criticisms from other security researchers, reporters, and companies. Since then there have been reports of exploits for this vulnerability being found on web sites, which has led Microsoft to create a tool that will disable the vulnerability.
Microsoft has released as temporary workaround that can be used to disable this vulnerability until an official Windows update is released. This fix can be downloaded from the Microsoft knowledge base article #2219475, and when run, will plug the vulnerability. It should be noted that Microsoft has stated that "Unregistering the HCP protocol will break all local, legitimate help links that use hcp://. For example, links in Control Panel may no longer work." In my testing with the fix, I have found no issues after running it.
In my opinion, regardless of what may become broken, it is better than being vulnerable to an exploit that could allows commands to be executed on your computer without your permission.