Fatal Error on Final?

I didn't see any threads about fatals particularly with SP1 and the 77W, so I decided to create a thread. I have had fatal errors occur during both of my 77W flights. On my first 77W from KLAX to RJAA in the ANA livery, at about 4 miles out I got a fatal error. No performance issues or anything else was noticed during the flight. This was about 10 and a half hours after takeoff, no time compression used. I then tried RJAA to KORD (same plane and livery, computer was restarted), about 12-13 hours. Right at the 100 feet GPWS callout, I got another fatal error. This flight though I encountered an repetitive issue with frames randomly dropping for a few seconds (to about 8-9fps and back to 30) and this occurred on about 30 second intervals. I also had issues with the autopilot in LNAV mode sweeping left and right from the flight path on descent. Switching to HDG and then APP had no issues. 

I'm not sure if this might just be a bad install of SP1 and the 77W, and I plan on reinstalling the plane. I just wanted to see if anyone else had similar issues. If I find these issues to continue, I might then consider filing a ticket. I've never had issues with the 772 on long hauls, so I am hoping this is something I can get fixed.