Error message in HFSS v.10

Could anybody help me regarding the following error message in HFSS v.10

>>Fast sweep setup, process abc3d : "WavePort1" mode 1 crosses cut-off in the specified fast sweep range. Consider splitting the sweep into multiple ranges. Use a port-only discrete sweep to locate the cut-off frequency.

I am badly need the solution....please help me!

Thanks,
ant_ebg

The first solution is to update to HFSS13!?!?! HFSS10 is insanely less efficient...

As for your error (seems to be self explanatory?!): Your waveport is exciting a mode(s) that is evanescent in the frequency range, ie cutoff. Fast sweeps do not support evanescent modes.

Thanks tallface,
First solution is not viable for me to right now, since all the project of mine is in v.10
Anyway, could you suggest me any probable solution.....
Hope for a reply :)