Numerous times my Windows Vista has been missing icons in the Notification Area. The icons that has been missing is normally Network, Volume and Power.
In Windows Vista you can easily enable these three notification icons, as well as the Clock, in the Taskbar and Start Menu Properties dialog, accessible by right-clicking the Start icon and selecting properties. But the problem is that I can't enable these icons when they disappear after starting Vista - they are disabled.
Multiple people have this problem, you can read more and see the screenshots here:
Missing icons in Windows Vista Notification Area
I know the how to fix this for the current session - remove “PastIconStreams” and “IconStreams” from the registry and restart the explorer. But I want to find out if someone(Microsoft?) has a permanent solution for this intermittent problem.