S Function gives error on Ctrl-D

Hi, I am using an SFunction from Dymola in my matlab model in Matlab 2009BSP1. Whenever I do an UpdateDiagram the SFunction reports an error and Matlab crashes. However if I click Start Simulation everything updates properly and the model simulates. Could someone help me understand why this could be.

Thanks a lot.

[Kaustubha Govind]

It is hard to tell with this information because S-functions can crash due to a variety of reasons. Do you have the source code for the S-functions? If yes, I would recommend debugging the S-function (see http://www.mathworks.com/help/toolbox/simulink/sfg/bq2rjeu-1.html for more information) to see what line causes the crash. If you don't have the source, it may be best to report this to the vendor.