What kind of software is this that is now messing up my ENTIRE computer??
Not the type that would have the ability to do that, e_jms. Start11 has been installed on thousands of PC without any such issues reported. It just reads like there is something else at play here - something fundamental to the PC.
If you are using restore points, it might be prudent to roll back to the most recent one.
As for the 2nd user issue, something that was not asked (but should have been), is that too an Admin account? If not, please create a 3rd Amin account to see if it too has the issue.
Stardock Product Lifecycle Manager