Sounds properly messed up just like mine. I have an 18 month old 27" imac which I bought as I got fed up with windows and pcs. I can't believe an update has messed up my system so much.
I tried the combo update as the app update has messed things up, no joy with that either, tried verify disk, fix perms, fix ACL...
My next step is to re-install and hope that works. My time machine backup stopped about a month ago but I have most of my files just in case.
I have to agree - when you pay a premium price you expect a better experience from say an update than one that completely messes up your machine. I switched to mac from pc so I wouldn't have to spend time 'fixing stuff' so i feel let down.
I have to question some of the actions in the last year including the iPad app google map fiasco, apple maps placed the Taj Mahal in my home town of Brighton, UK??