Kitty Mystery SOLVED

In my office there is an old Dell pc tower that nearly completely conceals a floor-level shelf--and that's where I found  my kitty has been hiding. Close to me but so still as to be concealed. I have her at my feet on a throw rug and am watching her VERY carefully--she is quite upset and not herself..but not actually ill. If she doesn't snap out of it she's going to the vet