This can be usually resolved by the simplest way....
>>>>>> Go to the clean simulator option and click it.
Even after this if this does not work
>>>>>>> Locate the clean.bat file in the specific simulator's folder and run it
If this does not help too
>>>> Go to task manager and see if there is a BBdevManager or something sorts in in the processes tab,
if yes , then kill it... and then restart the simulator
Now you should be good to go :) :)