Hmm let me be detailed in case it matters. I'm 23 Raki Drunken Monk on Frengrot. I'm weilding Standard Issue Sentinel's Knuckles in primary and Dread Claws in secondary. (edit: I use the standard AI except for a map texture replacement and custom PoI points on the map so that shouldn't affect this.)(edit: I've been working on crafting for a week or so so I can't swear this is absolutely due to the patch. Today was about the first whack whack for me in some days.)
I was in Drunken Mastery stance throughout with the reduced cooldown timers.
My bug is with the Counter bar, which for me contains Quivering Palm I and Stinging Backfist III.
In combat, when the conditions allow for Flying Kick II to go off, if successful it enables Kick of the Heavens I. Now while the cooldown is moving down the icon so you can activate Kick of the Heavens I, say I dodge something, and get the "boing" sound effect that tells me that a counter is enabled. If I then do the Kick of the Heavens I, then that icon (for KotH) replaces the Stinging Backfist icon in my counters bar. I stays lit, it doesn't cool down or anything, and it knocks that ability off the bar.
At that point, I can only perform Stinging Backfist III if I drag the icon down onto a regular button bar. Of course being there, it doesn't show the cooldown animation or the activiation timer (green bar moving across the top) or anything.
The only fix seems to be to restart the Vanguard Client. Reloading the UI with uiload doesn't help.
I was able to replicate this 3 times today with restarts to get the icons back the way they are supposed to be in between. In each case, it was: Flying Kick, dodge counter becomes available, KotH performed, Stinging Backfist icon replaced in the counter tray with nonfunctioning KotH icon.
It's not just graphically displaying the wrong icon either. I have a macro that has all my specials prioritized in a list, and after the bug replaces the SB icon on the counter bar, an isolated dodge that should enable the counters and using the macro that should activate it doesn't trigger any more Stinging Backfists until I drag the icon from my abilities book down onto a normal button bar.
UPDATE 5/13/07 OK tonight it seems to have been fiddled with but now if Flying Kick is available, and I get a dodge, and I perform a Flying Kick, then Stinging Backfist is replaced by a nonfunctioning KotH icon.
I think the solution to this is that KotH needs to have an actual spot on the Chains bar or something, along with all the other finishers. I know it is an "advanced finisher" but fine, as it has been it really has no home, I have never been able to figure out how the icon is supposed to work, replacing Flying Kick while it's available would make most sense/least harm in my mind since you need to successfully do a Flying Kick to trigger it. But only if the Flying Kick icon came back afterwards

I say, skip the icon replacement strategy altogether because it is causing problems with the UI. Just make the Chains bar one icon longer, put the KotH icon on it and leave it dark until a successful Flying Kick (the prerequisite.) Problem solved. You already have a successful coding for icons staying darked out until prerequisite conditions are met (dodge, crit, whatever) so why mess with success.
As it is, it's popping up on the bar but at the wrong place, wrong time and broken, and not resetting what it replaced when it is no longer applicable. Tonight is different but no better than yesterday.