Chrysler: grand voyager '98 start blockade problem! HELP!

hi,

I need some urgent advise (also by email if possible) regarding the
following issue with my '98 Chrysler Grand Voyager. It sometimes
refuses to start, being the start blockade refusing to acknowledge
that I am using the correct transponder key.

I've been to Chrysler, but all they came up with was that I had to
knock on the dashboard to solve this! Funnily, this worked on one
occasion, but now it simply does not start anymore.

It appears to be a mass-problem in the dashboard and Chrysler has
added an extra mass-cable below the radio, but not succesfully it
appears.

Anyone got any ideas to solve this structurally, besides getting rid
of this (otherwise great) car?

regards,

Ruud