DirectShow leak after continuous creation/destruction of graph

Hi,
 
Bascially, I get a crash in a DirectShow application after hundreds of start/stop sequences.
 
I developed a simple application aiming to reproduce the problem and I get some strange behaviour at some point.
 
I may include the application code in a further post if necessary, but it based on
 
- OpenStartClip : Creates all the VMR9 stuff, including RenderFile and Run.
- StopCloseClip : Stops the graph and releases all interfaces
- The GraphEvent Handler : When receiving EC_COMPLETE or EC_USERABORT, posts a private WM_RESTART message to the application
 

Hence, the test application is supposed to play a file continuously by starting it again when finished.
 
The clip is a 6" WMV clip.
 
This works whell for about 1200 playback sessions, but at some point, it does not work anymore : playback is never started again.
Moreover, the last try session shows I got an unforeseen message in the GraphEvent Handler which code is 0x201 and is not documented (unless it is the WM_LBUTTONDOWN message which is not supposed to be triggered by DirectShow in the Callback).
Note that this message is triggered during the OpenClip treatment, as in that case I do not get the usuall EC_PAUSED I got when the application runs fine when starting playback.
 
Notice that I can exit the application propely, but I cannot start any new playback again while launching the application : I need to reboot the computer to get it work again.
 
This test was done with XP but I suppose it it the same with Seven as my general application stops on both OS after a while.
 
So the first clues are for me to know
- if some leaks are known in the DirectShow implementation process
- why I encounter this 0x201 error after hundreds of start/stop
 
I may provide the test code if necessary, but will avoid it in this first post in order not to pollute.
 
Thanks in advance.