Compiler stopped compiling

from Todd Grosvenor (
I was using the compiler that comes with Learning to Program C++ and all was fine. Then one Monday I tried to debug one of the samples that was included, and upon my first press of the f8 key, it exited to DOS. It does it every time I press f8 now and it's got me confused because I didn't change anything. Any suggestions anyone? I already tried re-installing it.