problem: shutdown time proportional to runtime

Hello Experts, I am developing a fairly large application using multiple que
ued state-machines as the fundamental architecture.I have noticed that the s
hutdown time of the application, i.e. in the IDE after the final VI terminat
es there is a noticeable de
lay before the VI returns to edit mode.The odd thing is that it is proportio
nal to the length of time the main VI has been running.My first thoughts wer
e an unbounded array growing (and then being released) but the memory usage 
of the application is rock
solid.Then I thought, it could be a reference opened somewhere and not close
d, but I am not really doing this at all in my application. I am using contr
ol references a lot, but you dont need to manually close these do you?I cann
ot think of anything else w
hich would be "building up" inside the application as it runs. All the queue
s are sensible sizes, and the final VI actually closes in good time, its the
 delay after this that is troubling me...I do not have any custom DLLs in th
e application, and only one
activeX control (which I am going to try and disable now to see if this help
s)Any ideas?