Andreas Raab uploaded a new version of Kernel to project The Trunk:
http://source.squeak.org/trunk/Kernel-ar.249.mcz

==================== Summary ====================

Name: Kernel-ar.249
Author: ar
Time: 21 September 2009, 10:20:18 am
UUID: e21b2985-4367-5342-8fa3-87a10df7a4d1
Ancestors: Kernel-nice.248

Put the delay guard back which prevented scheduling the same delay multiple times. It got accidentally removed in a recent cleanup.

=============== Diff against Kernel-nice.248 ===============

Item was changed:
  ----- Method: Delay>>schedule (in category 'private') -----
  schedule
  	"Schedule this delay"
+ 	beingWaitedOn ifTrue: [^self error: 'This Delay has already been scheduled.'].
  	resumptionTime := Time millisecondClockValue + delayDuration.
  	AccessProtect critical:[
  		ScheduledDelay := self.
  		TimingSemaphore signal.
  	].!