This is going to sound ridiculous, but make sure that you aren't pressing both the brake pedal and the gas pedal at the same time. The two pedals are very close together in our VX's and sometimes, like in a panic stop, you can end up hitting both pedals at once.
This has actually happened to quite a few people here including myself.
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless