[H] Windows installer problem

[Thane Sherrington]

I have an XP Pro SP3 machine that appears to have a Windows installer 
problem.  When I install a program (it appears to be only 
InstallShield installers) I see the window saying that InstallShield 
is configuring the Windows Installer, and then I get a Window 
Installer window, the one that gives the msiexec options.  (You can 
see it if you run msiexec from the command line.)  I assume that 
Windows Installer or Installshield has gotten damaged, but I'm trying 
to figure out if it's fixable.  I've tried upgrading InstallShield 
and tried reregistering Windows Installer, but with no change.

Any ideas?
T