the message in the title appears and it never used to help

Perhaps you have another game running in background?

More information would be nice

things like;
What OS you are using?
What version of LFS? standard or test patch?
What, if anything have you changed in your HW or SW? maybe new GFX card? or driver?
Have you run (start/run) "dxdiag"? and does it pass all the tests?
Are other games or programs giving similar errors?

The more info you can give the faster it should be for someone here to rule out what it is not, and maybe get to what it could be or even what it is, that is causing your problem.

Good luck.

SD.