There's relief on that in the new version: PhaseOne's Media Pro.  See my post in this topic: 1310 Error - http://thedambook.com/smf/index.php?topic=2243.0

W. Fritts

PhaseOne, the new owner of iView Media Pro/Expression Media and now just Media Pro, has released a new version on May 10th, Media Pro, which eliminates the 128,000 or  2 GB catalog file size limitation.  It's integrated with PhaseOne's Capture One application. 

As an amateur much of the enhancements will not be critical to me but one is.  the GUI. It's the dark background type that's so popular these days.  From my point of view, i.e. older eyes, I find the contrast low and much more difficult to use. There was some discussion on the GUI in their forum and PhaseOne did say they were open to change depending on the demand, etc.

In the left hand pane of the Organize Panel individual areas, i.e. Catalog Sets, Keywords, etc., cannot be increased or decreased in size. They can only be fully open or closed.  Makes it more difficult to view portions of the Catalog Sets and Keyword areas as the same time. Takes a little getting used to.

W. Fritts

There may well be a hidden file, probably in your User/Library/Preferences folder, that is blocking.  Create a new user on your Mac and try installing and running it from there.  Or better yet, on another Mac entirely if you have access to one. 

W. Fritts

There are some serious consequences to using a "referenced" library as opposed to a "managed" library where iPhoto copies the files into iPhoto upon import and handles all aspects of file management from there on.

1 -  you are taking responsibility for the source photos which means you will have to delete them manually if you delete the photo from the library.  iPhoto will not do it.  They cannot be renamed or moved without breaking the links and messing up the library.

2 -  if you move the location of the source files and they are on a different volume than the library the link between the alias files in the library and the source file will be broken.  You will have to relink each photo when iPhoto asks.  Sometimes linking one photo in a folder will relink all of the photos in that folder.  It's not 100% reliable.  If the library and source files are on the boot drive relinking in the event of changing location of the source files is automatic.

3 - if the source files are on a different volume and that volume is unavailable when iPhoto launched or unmounted while iPhoto is operating the links will be broken and have to be relinked.

For serious amateurs I would recommend using a DAM app like Expression Media and iPhoto just for special projects like books, calendars, slideshows, etc. it's not anywhere near capable for professional photo management IMO.

W. Fritts