I am (was) running GS3 as a slave to Cubase VST 32/5 in rewire mode. Everything was working perfectly, but I just recently launched GS (after launching Cubase of course) and GS launched in standalone mode, and Cubase did not recognize any rewire channels--the only thing I changed from when this setup was working properly, was the number of rewire channels in GS Config (switched from 28 to 2, just playing around). Now every time I try to launch Cubase--->GS, neither app recognizes the other! Any thoughts??
Nevermind--I uninstalled then re-installed GS and all is well again.
And in case anyone is interested, GS3 works quite well with Cubase VST 32/5--I think my error derived from the fact that I placed the GS3 app on the desktop instead of just creating a shortcut, which screwed things up a bit
(I guess not many--if any-- folks are using this combo since SX is the new 'fair-haired child' of Steinberg, but it works quite well)