Windows XP sometimes displays the following error message: “Windows Installer service could not be accessed. This can occur if you are running in Safe Mode or if the Windows Installer is not correctly installed.”

This was probably caused by a damaged registration service. To repair the registration service, follow these steps:

• Open cmd.exe by clicking Start, then Run and typing cmd. Alternatively, you can find cmd in Start, All Programs, Accessories and selecting Command Prompt.
• type msiexec /unregister and press Enter
• type msiexec /regserver and press Enter
• close cmd window

This should resolve the problem.

Another solution would be to go to the Windows Update web site (http://windowsupdate.microsoft.com/) and install the latest Windows Update software. If you already have it, then make sure you have the latest service pack and all critical updates.