Occasionally when installing software you may receive an error message to the effect that 'Windows Installer could not be accessed' or some similar message. This could indicate that the Installer is actually damaged and needs to be reinstalled. The following procedure will allow you to reinstall the installer without having to completely reinstall Windows XP.
The instruction below are adequate for systems running Windows XP with service pack 1 (SP1). However, if you have updated your Windows Operating System to service pack 2 (SP2) then you may find that you receive an error message to the effect that c:\windows\system32\dllcache could not be found on your system. This basically means that you are unable to continue with the instructions.
Although Microsoft have a redistributable download of the Windows Installer 3.0 available it cannot be used when Windows XP Service pack 2 (SP2) has been installed. The reason being that SP2 already has the Windows Installer 3.0 software added and, because of file protection, would not allow the Windows Installer file to be replaced.
To that end one is faced with two options regarding the replacement of the Windows Installer. One can either reinstall the Windows XP service pack 2 (SP2) (Obviously it would be wise to 'uninstall' the service pack SP2 prior to attempting to reinstall it, assuming, of course, the update wasn't installed from a slipstreamed copy or from a boxed copy of Windows XP including SP2) The alternative is to do a Windows XP repair in order to reinstall the Windows Installer. To do a 'repair' see: 55. How Do I Repair My Windows XP Installation.
1/ Click the Start button.
2/ From the Start menu click Run.
3/ In the Run dialog box type: cmd and press Enter.
4/ The Command Prompt window will now appear.
5/ In the Command Prompt window type the following pressing Enter after each entry:
6/ After Exiting from the Command Window Reboot your PC.
7/ The Windows Installer should now automatically be reinstalled.