I agree that the Microsoft OS errors can be hard to track sometimes, the reuse of some number ranges for specific modules can make diagnosis difficult.
However, in one article on MSDN, OS error 126 is defined as ERROR_MOD_NOT_FOUND, where MOD is an abbreviation for module.
Couple this with the page full of reports on support.sas.com that link OS errors and the incorrect path or system variable defining locations of modules and I'll wager there is some system variable or path definition you need to complete for this to work. Searching all relevant documentation should guide you to some installation requirement that is yet to be met. If it doesn't, Tech Support will have or will find exactly the answer you need.
In passing, two things are worth commenting on: one of the SAS Support notes refers to OS error nnn not 126, which means more than one error code has been produced. So when you search the SAS site, don't always expect hits on the error number. Windows is an arcane art sometimes, as I implied with my comment on error tables above.
The second point is that if it has never been made to work, then this isn't the result of installing some other piece of software you'll need to uninstall. This is GOOD news, since updates and patches by Microsoft on Windows have an often deserved reputation for causing more grief than they are worth. Mind you, I have seen a couple of anti virus packages commit some horrid acts on update as well, so it is the OS that probably has some critics to answer, rather than the patch distributor.
Good luck in finding your missing install option.
Kind regards
David