I have Run time error problem

Here is my situation
Note: Brewers Cleanup option is selected from Advanced Web options

I have 15 independent scripts running from Quality Center (Test Director). When I run all scripts from Test Lab, after 10 scripts successfully run, when the 11th finish and try to close QTP during that time I get an error message box it says

Message box Title is: Microsoft Visual C++ Runtime Library
Message is :
Runtime Error
“Program C:\Program Files\Mercury Interactive\Quickest Professional\ bin \ AQTRmtAgent.exe”

Abnormal program termination

If I keep Browser Cleanup option is uncheck (default) then I do not have problem