ERROR IN COSIMULATION VSIMK.EXE STOPS WORKING

hi , when iam running hdl cosimulation error message shows "vsimk.exe" stops working and then simulation ends with error message showing server not conneting

I AM USING MATLAB 2008A, AND MODELSIM DE 6.3F " vsim "command works correctly with out any errors but why ? the error comes

[Kaustubha Govind]

This is not enough useful information. Please provide the exact error message and whether you have been able to run one of the demo models successfully.