my iMac crashes using iPhoto, the database constantly needs repair, and upgrading software patches causes the screen to hang

I am not sure what is going on. I have kept current with all upgrades and now when I attempt upgrades my system will hang on the white screen, forcing me to turn the machine off and on.

iPhoto has been really buggy (latest version) - keeps telling me that I need to repair my photos. Last night I was working on a photo book and it crashed twice.

Once it rebooted the iMac, the second time while uploading the book it crashed iPhoto.

Since this is past apple care - I am not sure what to do. I am in the US and I can't find any information on pricing for a visit to the genius bar.

The only thing I have going on with this machine is two seperate user accounts that access a shared iPhoto and Music library on the shared portion of the HD.

Thanks for any help.