After entering credentials and turning off the screensaver on OSX 10.6, applications no longer respond to user control.
This is caused by a bug in the operating system involving timing. Anything using the screensaver module in /etc/authorization can potentially see this issue.
Resolution # 1
Apple will be releasing a fix for this issue in a future version of OSX 10.6
Resolution # 2
Quest has provided a workaround in later versions of Quest Authentication Services. Upgrading to version 126.96.36.199 or higher will include this fix.
For possible issues concerning the screensaver and disconnected authentication please see this solution.