can't run game through xcode; works when launched from iphone

Hi there. I'm running unity 3.2.0f4, with XCode 3.2.5, and iOS 4.2. I've had this configuration for some time now without problems.

I'm not sure why, but all of a sudden my app cannot be run through xCode, which makes it particularly difficult to debug.

The build completes with no problems, but soooooometimes (I think when I switch over to armv7, whatever that is) I get the following error when it goes to install:

Uncaught Exception: -[PBXDebugScriptCommand debugSessionDidStart:]: unrecognized selector sent to instance 0x2013d3580

Stack Backtrace: The stack backtrace has been logged to the console.

anyway, if the app does get installed with no problems, when it starts to run, it crashes. if i go to the console, I get:

Running Error launching remote program: failed to get the task for process 499. Error launching remote program: failed to get the task for process 499. The program being debugged is not being run. The program being debugged is not being run.

although this instance says "499" - i've gotten a whole pile of other numbers. seems it's different every time.

At this point if i go to load the app from my iphone dashboard, it loads fine.

Let me know if you've got any ideas...