Finally somebody else has encountered the problem - at least I think it's the same. See FP in X-Fonter below and my post in the Spybot S&D forum.
Did the suspect process come from a file named is-xxxxx.tmp? I believe that's an Inno Setup file. If it's coming from some other setup program, that means the problem is more fundamental.
I have not found any way to get the install to run without turning off Teatimer. I can see where you might be reluctant to do that for a downloaded program, but mine was a program I wrote myself.
Fran