Videos don't work on IE8 or Firefox, have tried all I can think of. Please help?

Question

A bit of background.
My computer runs Windoxs XP 2002, with Service Pack 3. About two months ago I noticed that youtube did not work on IE7, so I recently downloaded IE8...needless to say videos still don't work (on youtube and bbc amongst others). I have Adobe Flash Player 10.1.102.64 (the latest I think).
By don't work I mean that when I go to bbc the vidoes either appear as a still, which one would normally click on to start, or they appear blank / white. When they appear as a still and I click on the video, the place where the video was goes blank.
Youtube loads really strangely (I think kind of like HTML version) and no vidoes work.
I have checked that all add-ons are enabled, and my Java is up to date. I have also fiddled aroud with the "enable hardware acceleration" but to no avail.
On top of that I have uninstalled and re-installed both flash player and IE8 (the second time I downloaded IE8 I clicked on the 32 bit version). When installing flash player I used the desktop version and disconnected from the internet just to make sure.
Having looked on some forums I tried Firefox but again no luck. I am getting really frustrated as I have no idea what to do.
In terms of do I operate 32 bit or 64 bit, I don't know (if someone could tell me how to find out then I will).
Please can someone help?
Thanks
Will

Answer 1

Adding the read permissions to the registry key as noted above fixes the problem when the 'read' permissions for "USERS' is missing.
In systems I have checked the key has the USERS permission ACE before 10.1.102.64 is installed and missing after the installation.
On Windows Server 2003 the key inherits 'Authenticated Users' instead of 'Users' which should be true for all systems post-XP.  The inheritance seems to be removed and keys are not copied in correctly.
I believe, and this should be checked with Microsoft, that the inheritance needs to be restored and the root of CLASSES/MIME.  This is what I have chosen to do as this is the way it is on all working systems.
The error may be caused by one of the trojans that has attempted to exploit Adobe Flash as this would cause Power Users(this account is missing too) to install a new control.  They could then be redirected to another rogue site where malware could be installed.  All of my systems run as standard users and I only run as admin to do installs and repairs so this exploit would not easily work.
This is a good warning to not run as a Power User.  As Administrator the exploit won't trigger as the administrator ACE has been copied to the key.
I believe this may be a good example of an 'Elevation of Privileges' type of exploit.  This is the Find-A-Hole-And-Make-It-Bigger Exploit (FAHAMIBE) Say that three times fast.
Kidding aside.  I hope this is useful to somebody but may not be the cause of all errors like this one so check very carefully.
I don't think this is caused by the newest Adobe installer or release.
Message was edited by: jvierra21