Looking at the TTU 13.0 compatibility matrix, it shows that both SQL Assistant and Query Scheduler need to be running in 32-bit mode on the Windows 7 64-bit. When running in 32-bit mode, both need to be at a certain patch level.
Teradata Query Scheduler 13.00.00.04
SQL Assistant 13.00.00.16
If you are at that patch level or later, then submitting a GSC incident for analysis would be the next step.
SQL Assistant does not contain the error message "Query scheduler start up error", or anything even remotely similar.
It does check to see if TDQM/TQS is installed during startup... but this should not cause anything to execute.
It looks for the file "tdqmsubm.dll" - probably in C:\Windows\System32.
If you have previously had TDQM/TQS installed maybe the un-instal failed and this file remains on your system. (Or the file somehow got copied to your system)
Try deleting this file if it exists.
It did work for me.
I have the same problem. I discovered that I get the error when running as an ordinary user, but not as an Admin, so it seems to be permissions related. Unfortunately Process Monitor didn't seem to point a smoking gun at exactly where the problem lay.
I worked round the problem by installing without the Scheduler components as they weren't actually required, so sorry I can't give a definitive fix, but the above may help.
Incidentally I noticed that the strange problem where files install to C:\Program Files (x86)\(x86), went away when I installed without the Scheduler components.
Update: To run the Scheduler users require the Create Global Objects right.
Administrative Tools, Local Security Policy. Under Security Settings, Local Policies, User Rights Assignment, Create Global Objects. Users or groups can then be assigned this right.
Looking on an XP workstation, Interactive users appear to get this right by default. On Server 2008 it appears they don't. I haven't checked Windows 7.