I agree with the other posts thus far, but what has saved my clients and I (emphasis on I as using it myself for a while now) is Revo Uninstaller. This does a LOT more than any other uninstaller program not found on a non-Dos command line prompt. Perfect for MS platforms IMHO.The ability of it deleting and detecting Registry lines of code re: whatever program u are uninstalling is AMAZING from a non-command line GUI.

But remember, ALWAYS back up everything & Restore prior to uninstalling anything. Easy to say but only 10% of my clients do it, which in today's computer age is mind boggling.

While performing the following steps, reboot after each removal operation. The reason is to remove running programs and services and to release file locks.

1. A very simple solution is to install the offending program again, then uninstall it.

   If that doesn't work, i.e. if the broken installation hinders a new installation, you have to clean it out as follows.

2. Use the Windows Installer CleanUp Utility to remove the remains of the offending program.
3. Reboot and try again to install the program, then uninstall it. If this also doesn't work, proceed as follows.
4. Clean out all remains manually. Remove the files and folders of the offending program, usually a subfolder of the "Program Files" folder.
5. Clean out the registry. Fire up the registry editor, regedit.exe, and navigate to the following two registry keys:
   

   HKEY_LOCAL_MACHINE
    \Software

   HKEY_CURRENT_USER
    \Software

   In each of these two locate the name of the manufacturer and inside that or directly, if the software is only there under its own name, the key of the program. Check whether you have found the right one by snooping inside a little, trying to find recognizable clues, then delete the whole program key.

6. For good measure you can also search the HKEY_CLASSES_ROOT hive, using regedit's Edit, Search function, for the name of the program and delete the entire keys in which it occurs.

Don't forget to reboot after such an operation. And be careful—deleting anything outside the program's own key can damage your Windows installation.

If you're unsure about these procedures and want a way out if things go wrong, set a restore point before beginning to edit the registry. If things do go wrong, you can simply set your system back to that restore point.

Remember, there is always a residual risk in such operations to damage the installation. If you cannot bear that risk, make sure you have backups of the entire system, to which you can return in case of trouble.