Error optimizing a query: "BufferedGraphicsContext cannot be disposed of because a buffer operati (4226132)

The following error occurs during the optimization process of a query:

The following unhandled error has occurred:
BufferedGraphicsContext cannot be disposed of because a buffer operation is currently in progress.

Cause of issue may relate to  issues with memory or .NET Framework 2.0.

WORKAROUND 1:
Try adjusting Optimization Intelligence level under Options | Tuning Lab | Optimization

WORKAROUND 2:
Try optimizing in Batch Optimizer instead of Tuning Lab. The same  intelligence level set for Tuning Lab will be applied to Batch Optimizer.
(It is advisable to review Execution settings for Batch Optimizer before running, since this will process optimization and execution at once, and all possible alternates will be executed for run time stats. This could cause the job to run for longer then expected).

STATUS:
Waiting for fix in a future release of Quest SQL Optimizer for Oracle.