Memory Leak using LINQ?

Dear all,

I created a windows forms application using LINQ to connect to an Microsoft SQL Server 2008. The database is acessed appr. every 5 seconds. By using an profiler (and even the task manager after some time) it's clear that my application has an strong raising memory leak. The result of the profiler was, that objects created by LINQ were not disposed. After a runtime of an couple of hours the used memory was about 100 MB which is far far to much for such a small application.
After some research I put the LINQ connection into an using block but without any effect.
Is this a bug within LINQ or do I make an mistake in using LINQ?
If requested I will post the source code next time.

Thanks in advance.

Best Regards
Gerd Blake