Pixhawk Gyro drift and increasing temperature

Hi all,
I have a quad with original 3DR Pixhawk, 3DR GPS (Neo-7n) + compass and power module.
It was flying fine one month ago, and without any hardware/configuration change, it suddenly stopped doing loiter correctly. It flys fine in stabilize, but as soon as I change to any GPS dependent mode, the quad wants to fly away (not always in the same direction)
I’ve done everything I could think of:
Reflashed arducopter firmware
Reset PIDs to default
Recalibrated everything
Change pixhawk to another and gps + compass too
But it still behaves exactly the same!

From the last log, see a temperature increase of about 6 degrees and EFK1 -> GZ increases too.
NTUN -> VelX/Y cannot follow DesVelX/Y,

Here is one log from one month ago, when it flew fine: LINK
Here is a recent log : LINK

What is going on with this ? Why it is behaving like this ?