Windows Installer could not be accessed errors

[Cheryl]

I recently noticed that I'm getting the above error whenever I try to install
or uninstall any software using MS Installer. I don't know when the problem
first appeared because it's been quite a while since I last tried to
install/uninstall anything. I've gone through all the lists of suggestions
for fixes on this problem and nothing seems to be working. I've done the
unreg/regserver, I've renamed the msi exec/dll files to reinstall, I've
downloaded V3.1 of Installer and installed that, I've checked the permissions
and exe location in the registry, I've checked the service is manual startup,
I've tried disabling my virus checker, but nothing is working.

I'm on XP Home SP3. Can anyone help?

 

[JS]

How to re-install Windows Installer:
http://xphelpandsupport.mvps.org/how_do_i_reinstall_the_windows_i.htm

Also:
Common Windows Installer Problems
http://support.microsoft.com/?kbid=555175

Windows Installer CleanUp Utility
http://support.microsoft.com/kb/290301

Windows Installer 4.5 is available
(supports XP SP2 and SP3)
http://support.microsoft.com/kb/942288

JS
http://www.pagestart.com