Aperture continues to crash

Aperture is continuing to crash, sometimes on load at other times after a few minutes. I am running Aperture 3, imac 27", Lion 10.7.1. My Aperture library is rather large - close to 600GB which possibly is causing some issues?

Initially I referred to http://support.apple.com/kb/HT3805

I will list some of the approaches so far that I have tried in rough order.

Whilst running 10.6._

Repaired permissions with disk utility - not fixed.

Ran all the checks and repaired the database through aperture multiple times (holding option and command) - not fixed

Made a copy of the library and attempted to run it from an external drive - not fixed

Removed all preferences from the library folder - not fixed

Removed all plugins - not fixed

Deleted and reinstalled Aperture - not fixed

Decided to fresh install OS, figured I may as well upgrade to Lion, so I upgraded to Lion, brought old system across from time machine backup - not fixed.

Whilst running 10.7

Tried a couple of the above methods to no avail

Deleted my Aperture library and imported from a vault copy (losing a very small amount of pics and edits) - crashed half way through the first time but the second time it worked.

Aperture could be opened and worked rather well for a week and a half. I had the occassional crash, at times with a Nik Software plugin but not always.

Opened it today and once again it is crashing on start and also crashing when repairing the database.

Aperture opens for a few minutes and after crashing on database rebuild it appears to be missing a few pictures.

On closing aperture it now says "updating library 123xxxxx of 197000"

The crash initially appeared to be triggered when a certain project opens which also happens to be the wedding I need to have edited in a week.

I am moving my library to referenced masters so as to have more access in case of future crashes. All pics are backed up so that is ok. I am considering the move to Lightroom but would really rather stick with Aperture which I love when it is working.

Any suggestions or help would be most appreciated.

Thanks in advance.