Installed Composer 2016 Update 1, now VS 2015 Community won't lauch

I had VF 13.0 working fine in VS 2010.

I installed VS 2015 Community with C++ custom install, used it ok.

I bought and installed Composer 2016 Update 1, said it installed fine in both 2010 and 2015 VS.

Now VS 2015 won't launch at all, just a blink when clicked.  Note VS 2015 on drive E, 2010 on drive C if it matters (shouldn't).

Any ideas, now my VS 2015 borked...

Thanks, Ian