UPDATED: This issue appears to be fixed with the latest 10.6.8 OSX update from Apple.
I spent several hours this evening dealing with a crashing problem with the App Store application under Mac OS X 10.6.7. The problem is that when you start App Store, it crashes and presents the following unexpected quit log report:
I google’d the problem and found several forum posts about similar issues with App Store after upgrading the OS. However, I tried doing what the answers to those issues indicated was necessary to solve the problem. Alas, for me the problem didn’t get solved. Then I discovered that I had a vpn connection open to my workplace via Juniper Network Connect version 6.5.0 (build 14951). I tried signing out of the vpn and when I then tried to bring up App Store, it came up without error. I found out that it doesn’t matter whether Juniper Network Connect is running or not, it only matters that you do not have a vpn connection open at the time you try to bring up the App Store. So if you just sign out of a vpn connection, but leave Juniper Network Connect running, App Store starts up just fine.
I post this here so that it might help others struggling with this same problem. Check that you don’t have a vpn connection open when you try to use App Store.