Hi, Val,
Sorry to hear you're having trouble. We've just been doing the math and haven't had that many issues (just that there are bugs here and there in the computer program, and I would have thought the program has been around long enough to be totally de-bugged). We're happy overall, plus DD loves being able to work at her own pace. But it's good to know that there might be such problems with other courses. Good luck getting it fixed.