Well, the problem(s) atill exist with a PS/2 keyboard plugged in as well.
Of course, having no keyboard plugged in (Neither the USB or PS/2) results in the same problem of the player movement/input locking in one direction every now and then.
I've tried all sorts of Keyboard repeat and input delays as well, but unfortunately the same results.
It occurs for me under Win 7 Home Prem 64 bit with and without SP 1.
I'm hoping somebody/somewhere has a solution...
Test games where the problem is evident...Pac-Man, Ms. Pac-Man, Mr. Do, Dig Dug...
Never had any problems with my good ol' P4 and XP Professional.