I too have been stuck on copying framework.dll for a long time but I'm gonna take a guess as to what the solution might be.
First, even if you cancel the update when you get that message, your version in about says 920.
Recently, I uninstalled microsoft visual c++ redistributable because I had some notion that I didn't need it. Of course some programs started behaving weird, some wouldn't even start.
First, I thought net framework, in my case 2.0, was damaged so I uninstalled it and reinstalled it. If you don't know, visual c++ 2008 installs with net framework 2.0, atleast to my knowledge so after the reinstall everything was fine and dandy.
Then I figured, why not update visual c++ to the 2010 version? Did that and then out of nowhere comodo said updates were available, I clicked ok and it updated without a hitch!
I think visual c++ is the key but it's just a guess, nothing scientifically proven
If you don't have it, download it from microsofts download center and try the updater again.
Hopefully it'll work!