Progress Indicator incrementing gives exception

FROM : Kamal Shah
DATE : Tue Mar 29 15:27:31 2005

I have a method in which I am incrementing a progress indicator by
using:

[progressIndicator incrementBy: (float)(100/numFiles+1)];

This line gives the following run time exception in the console:

Exception *** -[NSNextStepFrame contentAlpha]: selector not recognized
raised during heart beat. Ignoring....

This same exception is shown repeatedly on the console.

If I comment the line, the exception does not appear.

Any ideas on what could be wrong?

Thanks
Kamal