I use four PCs on a regular basis (two work PCs, plus a laptop and desktop at home), and all three run Windows -- one Windows Server 2003, one Server 2008, and two Windows 7. All of these boxes are either on 24x7 or hibernated between uses, so the only time I reboot them is to install Windows updates.
And every... single.... time... I reboot any of these machines, I see one of these:
I typically go ahead and let Flash do what it wants to do, and yet it keeps coming back, over and over and over again. Based on this, I'm forced to conclude that either (1) Flash isn't really updating correctly, or (2) it really does have a new update to install every single time I reboot.
Neither of these is acceptable. Adobe, you're not building an OS here. Get it right and get out of my way. If there's a *real* new version or a *real* security disaster, then let me know about it, but I just refuse to believe that there are really that many emergencies that you need to install something every single time I reboot.
If you're wondering why folks like Apple have made such a big stink about getting Flash off their systems, this is exactly the sort of issue they had in mind.