I have a random-vibration model that's run successfully over the last few months, but now when I try to re-run it I get the following error message:

Input number of frequencies instead of upper bound frequency and rerun the analysis.

I've tried re-meshing the model and then just running the frequency part, but I still get this error.  And I don't want to simply change to inputting the number of frequencies; I actually want to run the model with the upper-bound frequency option.

Any ideas what could be the problem?

Thanks,

Dave