Vista - Memory Leak?

I do not know whether this problem is in Vista-64 or in Office 2007.
I have Vista-64 RC SP1 (Build 6001) and Office 2007 SP1
Over the last few weeks I have found that my OS gets very sluggish after using Office and after using the <insert clipart>. This happens in both Word and PowerPoint, so It seems that it is a wider problem.
I opened Windows Task Manager and examined the Processes. The process MSTORDB.EXE *32 (Media Catalog Object)opens and runs when the clip art function is used. However, after Office is closed -- yes completely closed -- this process continues to run and begins to increase CPU usage and its memory usage continues to increase, thus slowing down the OS.
Sounds like a classic memory leak problem to me and the only way I can stop it is to manually close the process.
Any ideas?

Well, I have got to the bottom of the problem, if anyone else is interested.
I turns out that my Clip Organizer database was corrupted. After running a <Tools> <Compact> from the Clip Organizer tool bar the problem was fixed.