Mark,
It is not a joke, it is VFP telling you that it is hosed. You can translate this message to,
"I am choking on a chicken bone, but I cannot tell you that I am choking on a chicken bone because I am choking on a chicken bone."
VFP is in a state that it cannot resolve the error message it has received from the OS and it cannot recover from the situation. The most stable reaction for you is to quit VFP and start it again. VFP is in an unknown state and continuing may cause untold problems.