Is it just me, or is it half the time when you win a match, and immediately click the "score screen" button, SC2 greets you with "YOU HAVE LEFT THE GAME!"
Is it still registering correctly in my stats that I won? Does this happen to you?
I do stuff and thingies... Try widening and reducing the number of small nooks and crannies to correct the problem.
Watch your match history screen and check the entry. That should state what happened.
It updates properly to "you win" within 20 seconds or so of you opening it IIRC.
None.