Windows 7 - Error 1721/Windows Installer error

Hi, I didn't know where else to poste this. I also searched the forums & couldn't find a specific answer or resolution.

We've recently upgraded to Windows 7. I am trying to reinstall a program we have called HomeTech Advantage onto each computer. It's worked on 3 out of 5. The other two give me this error when running the setup file:

Error 1721. There is a problem with this Windows Installer package. A program required for this install to complete could not be run. Contact your support personnel or package vendor. Action: DWUS_Unregister. C3A146F5_4B48_11D5_A819_00...

Support from the vendor is not available as we haven't renewed our support subscription. Any help would be GREATLY apprecaited, as I've already researched & tried several things to no avail.

Thanks in advance.

Check the computers which succeeded in installing the program to see if they have any MS Net Frameworks which the other computers don't. Show MS Updates in Control Panel>Programs and Features.

Ok I did that check, found they did have more updates installed so I did Windows Update installs on the ones not working & tried again - still same error. The two pc's getting that error now have more Updates installed than the ones that worked fine with it.

Did you look to see if the computers which succeeded in installing have Net Frameworks which the other computers don't have.

Look in Control Panel>Programs and Features list to see as they might have been in an installer and not arrived via Windows Updates.

I just checked for .NET Framework specifically & found: 2 of the 3 that succeeded have .NET Framework 1.1, one has nothing. Mine, which is one that did NOT succeed, also has .NET Framework 1.1.

Try running the program in Vista or XP compatibility mode. Right click the .exe file, select Properties, then on the Compatibility tab select Vista first and then XP if Vista fails. Also click Run as Admin. Now run the .exe.

What I would do if I have to have those programs and they will not install, is save a Windows 7 Backup image externally of the current install. Then reimage onto the same HD a backup image from one of the computers that succeeded with install to see if Windows 7 will start up, swap out all of its drivers and run normally. I have done this about a dozen times when Windows 7 install fails and it always worked fo me.

Backup Complete Computer - Create an Image Backup