This usually happens if your PC's CPU usage is very high while you are recording.

If you are using GDI record mode, switching to MPEG record mode (go to Settings -> Record Mode / Performance) will usually significantly lower FlashBack's CPU requirement.

Other things you can do:

  • Reduce the size of area that you are recording¬†
  • Reduce the recording frame rate
  • Close any unneeded apps that are running in the background.