Need help with InstallShield error 1608...

I need help.

I've got a commercial Windows application which cost my client $1200. When I attempt to install it on any WinXP Pro computer (fully patched) I get an InstallShield error... "1608: Unable to create InstallDriver instance."
I've followed all the usual troubleshooting procedures, verifying Admin rights, DCOM settings, reregistered various applications in the Registry, installed updates and upgrades to the Windows Installer, reinstalled the network stack, etc. and many other things...

Of course I've had many conversations with the software vender, but no help there. They say it installs okay for everybody else...and then they send me a new CD.

I have found that I can successfully install the application on any Win98 PC and a W2k PC (only up to SP3) AND I can install it on a Windows XP PC SP2 providing there are no other applications already installed.

The PC I need to install the application on is a production PC in a Court Reporting Agency and has many many applications already installed on it. I expect that a reformat and fresh install of Windows and all applications would exceed 15 hours of work, which when billed out to my customer would end up costing over $1000 just to install an application which normaly should only take 15 minutes to install.

Please, can somebody point me in a positive direction?

Thank you. Kirk Lewis

sorry, the only thing i found was the troubleshooting page at Consumer Central and it appears you've take all those steps. This is the final step they say:

Thanks for looking...but that's all I've been able to get, too.

before updating the InstallShield, did you uninstall and remove all instances of previous versions of it? that's another issue i ran across in searches. i've only run into this problem once before and after reconfiguring the DCOM, i was fine. i'm just shooting in the dark here for you.

here's a link on the updates

No. I did not attempt to uninstall the previously installed versions of InstallShield.

Kirk