Yes, I am having exactly the same problem as Mark did. 

But there are some differences:

1) Although I have many sceneries as well, I don't have a big log file. It is about 1.5M. 
2) After freezed for about 5 to 10 seconds, my system and Plan-G resume to normal and work again; but
3) When I click any feature on the menu bar which creates a pop-up, it freezes again. 

In other words, the problem occurs only when pop-up activates.  Other than that, Plan-G works normally. 

I OC my HD 5870 from 890MHz to 970MHz.  I tried tuning my card to default but the problem remains.

I also installed version 0.91.  It doesn't have the freezing problem.  It started up with no problem but after I imported the data from FSX,  part of the background on the frame around the menu area is darkened. 

Everytime I re-start version 0.91, Plan-G shows up normally for about a second and then the area is darkened again.  It won't go away.

Looks like some incompatibility between Plan-G and Radeon card.

Hi,
Don't know if anyone is having the same problem I have.  When I try to click a menu bar item which opens a pop-up, my computer freezes and reports a "Display Driver stops responding" error.  Then it says the AMD driver fixes the problem and things back to normal until I click another menu feature.
I am using HD 5870.  I am having the latest driver but the problem have been existed since a few previous version back (both Plan-G and display drivers). 
I tried clean my computer and reinstall both driver and Plan-G.  Problem is still there.
Any suggestion?

BTW, where can I download version 1 or Plan-G?