I am getting a weird fault here.

The gearbox sometime just loose the gear while accelerating... Normally around 5000RPM.

It will feel like the car have lost the gear and will not rev. The engine lights also come on.

Once you stop the car, put it in park, shut the car off, and start it up again, everything is fine; engine lights goes away also.

It certinally looks like it is a electrical problem, anyone got any ideas?

bad ground? Gearbox oil?

I happen a few times now, and it is just worrying?

Any idea will help.

I am not sure about your model but it should have OBDII diagnostics and if you can get the codes read it may assist you in finding the problem as the fault code(s) will be stored in the ECU memory.