Have you checked this.
Are you logged on as admin user
Log on to the Windows XP computer with an administrator user account, and verify that you have the correct permissions for the C:\Windows\Installer folder. Follow these steps:
1. Click Start, click All Programs, point to Accessories, and then click Windows Explorer.
2. Click Folder Options on the Tools menu.
3. Click the View tab.
4. Click Show hidden files and folders,and uncheck Hide Protected Operating System files, agree the warning and then click Apply and OK.
5. Locate the folder C:\Windows\Installer.
6. Right-click the Installer folder, and then click Properties.
7. Click the Security tab.
8. Click System, and then verify that the Full control check box is selected.
9. Click Administrators, and then verify that the Full control check box is selected.
10. Click your user name, and then verify that the Full control check box is selected.
11. Click Apply and OK as required
Edited by Macboatmaster, 08 February 2011 - 08:13 AM.