I'm not sure if this is an C3D 2010 problem or not, but this is all I work in. Every so often my command prompt freezes up, plus my cursor does not work when picking a menu. If I press a key on my keyboard my pull down menu items display a single letter, like a "tool tip". The Home menu displays "H", the Insert menu diplays "I", Annotate "A".. etc.
All I can do is maximize and minimize my drawing, and that sometimes reactivates my command prompt but not always. Eentually my command prompt becomes active after 5 minutes or so, but I am not sure why or how.
Dell optiplex?
If so, I would consider upgrading to a better system starting with Win7 64-bit.
I figured it might be my machine. Getting a new computer is like asking for a year off with full pay. If it's turns on and boots up there no need to get a new machine.