Richard;
Sounds like a permission problem.
Are you an Administrator?
Local Computer Policy\User Configuration\Administrative Templates\Windows
Components\Windows Installer\
Local Computer Policy\Computer Configuration\Administrative
Templates\Windows Components\Windows Installer\
Always install with elevated privileges
[[Note: This setting appears both in the Computer Configuration and User
Configuration folders. To make this setting effective, you must enable the
setting in both folders.]]
=============
From:
"The Windows Installer Service Could Not Be Accessed"
http://support.microsoft.com/default.aspx?scid=kb;en-us;315353
Log on to your computer as an administrator.
Click Start, and then click Run.
In the Open box, type cmd, and then click OK.
At the command prompt, type: msiexec.exe /unregister, and then press
ENTER.
Type: msiexec /regserver, and then press ENTER.
Verify that the SYSTEM account has full control access permissions to the
HKEY_CLASSES_ROOT hive in the Windows registry. In some cases, you may also
have to add Administrator accounts. To do so:WARNING: If you use Registry
Editor incorrectly, you may cause serious problems that may require you to
reinstall your operating system. Microsoft cannot guarantee that you can
solve problems that result from using Registry Editor incorrectly. Use
Registry Editor at your own risk.
Click Start, click Run, type regedit in the Open box, and then click OK.
Click the following registry hive:
HKEY_CLASSES_ROOT
On the Edit menu, click Permissions.
If SYSTEM is not listed in the Group or user names list, click Add, make
sure that the local computer name appears in the From this location box,
type system in the Enter the object names to select box, click Check Names,
and then click OK.
Click SYSTEM in the Group or user names list, and then select the Full
Control check box under Allow in the Permissions for SYSTEM box.
Click Apply, click OK, and then quit Registry Editor.
Restart the computer. If the problem is not resolved, repair Windows XP. For
additional information about how to repair Windows XP, click the following
article number to view the article in the Microsoft Knowledge Base:
315341 How to Perform an In-Place Upgrade (Reinstallation) of Windows XP
+++++++++++++
Windows Installer Support Center
http://support.microsoft.com/default.aspx?PR=wininst