Workflow simulation error

Experts

I alwys have a hardtime to simulate the workflow in my local tools.

everytime i get the error message

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Siebel

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Still waiting on workflow process simulator. Please press Yes to continue, press No to exit.

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Yes   No  

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it works atelst 1 in 50 times ,is there any settings make the workflow simualtor works,

I try to delete all IE Sessions and restart tools ,still same,,any other solutions.

thanks

Matt