Hi

I have an automatic UK Crossfire and it's great fun. I have however noticed a problem twice recently. I have been travelling at speed (70+ but not breaking any laws) when the car appears to drop out of gear and will not select anything. Pressing the accelerator has no effect (other than to rev the engine). Basically the car has no drive and glides to a holt. If I switch the ignition off and on, the car will restart and select gears and allow me to drive. My questions are:

What am I doing wrong ?
What are the possible problems ?
What do I need do to fix this ?

The car is under warranty at present.

Any help would be appreciated.

Cheers