Mutex works in xp but not in vista

Hi,

I have written a code(mutex : singleobject) for single instance of installer.
That installer works fine in WindowsXP.
But when i run that installer in Vista, then installer will not allow to go ahead.
"One instance is already running error comes"( stated in the installer code ).
And installer will not allow to continue?

When i see the task bar come to know that that exe is opens two instances.
And when i search , i got to know that this is the Vista default behavior.
One exe is opening two instances.

I use two functions ( CreateMutexA() and WaitForSingleObject() )
Please guide me to get rid of this problem.

Hi,

Please help me to solve this problem, this is very criticle and urgent issue


Thanks

Difficult to say without a piece of the code