While in Combat i pretty much use mouse + keyboard, and if I'm strafing with the keyboard and I click on something, the key will often release.
Hold down the D key and W to make a right downward turn around an enemy. Click Fire all weapons, then click, rotate shield frequency, ship will stop turning and go straight until I hit the direction keys again.
In case this isn't clear. This is EXTREMELY ANNOYING.
I have had the same problem-- hitting Alt-shift and holding down the turn button ended up making my keyboard non-responsive in game. I could still use it in chat programs, other programs, but in STO it completely stopped working for a bit.