I recently decided to upgrade to RU6 MP2 from the original RU6.
From previous experience, in order to keep from having multiple SEP entries in my Add/Remove programs list while deploying/updating with SCCM, I have to disable the policies of "Require password to uninstall" and "Tamper Protection".
Normally I disable specified policie requirements, wait for the policy to go out to all machines and then push with SCCM. Once the installation is complete, I re-enable original policy requirements.
The above is what I normally do. During this particular upgrade, I forgot to disable the Tamper Protect.
After disabling passwords, but not Tamper, I exported my installation packages using the newest policy.
After numerous tries through automation and eventually manual and even logged installs, I still kept getting 1603 errors and some message saying setup ended before it could complete.
Eventually, after 1 full day of testing, I remembered to disable tamper protection. I was still getting 1603 errors.
On a whim I decided to rebuild my installation packages with the newest policy (password and tamper disabled).
Installs worked just as they should.
My best guess is that the supplied policy was getting applied during the install that said don't allow anything to "tamper" with the running exe's. Part of the installation process shutsdown, replaces and restarts those exe's, pretty sure that would be considered "tampering".
Even though I solved my own problem, I did alot of search here on the forum and I didn't see anybody who had done the same...so I thought I would post what I did.