It just hit me yet again. Really stopped counting how many times this happened with Origin.
However I want to update Accepted Solution.
Delete only:
Users\[name]\AppData\Local\Origin\Origin and Users\[name]\AppData\Local\Origin\WebCache
If you Delete* files from every 3 directories like suggested in the Accepted Solution Origin will start in default mode. Updating ALL games which are not in vanilla state.
Enough to say that for titles like ME2 or ME3 especially its murder.
* - Before deleting anything make copy of folders you're removing. That way you can always copy back, it will be still broken Origin, but it'll work as before. Deleting everything outright is bad idea - especially if you're running mods for games. Focus only on mentioned 2 directories first (real client cache).
I expect that it happens more often when using VPN. And so I do, often forgetting to disable it when opening Origin (O drops a loooot when play over VPN - then only game client which drops....)
And I agree with Althalus401. This basic flaw is basically ever present since I remember using Origin.