OK, two things to try:
Is your version of Flash Player up to date?
You can check here: http://www.adobe.com/products/flash/about/ to see which version you should install for your Mac and OS. Version 11.4.402.265 is for Snow Leopard onwards.
You should first uninstall any previous version of Flash Player, using the uninstaller from here (make sure you use the correct one!):
and also that you follow the instructions closely, such as closing ALL applications first before installing. You must also carry out a permission repair after installing anything from Adobe.
I get the same problem in Chrome as well and that uses a different version of Flash.
Also Finder windows are "sticky", not a Flash issue?
I've replaced Flash once already (but not uninstalled using the uninstaller), I'll give that a go later.
In Safari, nothing, running it clean. I have a few add-ons in Firefox but the problem persists even with Firefox closed.
As I said before, I have a lot of apps running - Magic Prefs, YouControl Tunes, BusyCal, SimpleTask etc but all of these have been there for at least a year, most longer and I haven't noticed any of them updating for a while.
Thanks for all your help so far - much appreciated.
I must confess that I am running out of ideas, but clearly something is acting like a bottleneck.
You could consider an Archive and Install:
How to Archive & Install:
and this also: