release resource

Question

Hello!
I have a form with several tabcontrol and resco controls on it. I realized that when this form closed, the memory state is not the same before calling this form.
So as I found not all resource is released, and aproxx. 1 MB is the different (leaking) each time I open and close the form.
I tried   .dispose method with each resco controls on the form.close event.
Opening 10 times this form causes notenoughmemoryexception.
Although by closing the whole application releases all the resources.
What can I do?
Thank you!