Is there a fix for the endless "Scanning for Steam games updates."?

On trying to fire up any game in Steam, or Activate a Product on Steam, a popup will display stating "Scanning for Steam games updates.", and just sit there. It never does anything, and only offers a Cancel button (which sometimes is even disabled), which doesn't allow me to start the game from Steam.

I assume it's never going to stop, it's been going for minutes, so, is there a way around this, a way to fix this, or a way to disable this scan?

There are a few things you can try:

• Restart Steam.
• Reboot your Computer
• Wait until its done.
• Rename the file ClientRegistry.blob to ClientRegistry.bak. By default you should find this file under C:\Program Files (x86)\Steam. This will force steam to generate a new .blob file and might fix your problem.
• Disable and exit steam-limiter if you have it

I've found that logging out (via change user) and logging in again fixed it for me

A solution that I have found is to go to steam>settings>account then click the "change" button next to beta participation and choose to participate. This works because the latest beta update fixes the problem.

It is sometimes sufficient to kill Steam.exe from the Task Manager, then launching it again.