Thanks to all for their replies.

I have a Platinum canopy cover, which I use prior to flight. The
problem occurred 3.5 hours later, after landing. The canopy cover
wasn't used for the 5 minute tow to the trailer, and the canopy was
closed during tow. I'll be more vigilant next time its so hot - naybe
Eric's foam block idea would be simpler post-flight than the cover.

What is the physical mechanism whereby the touch screen gets flaky
with heat? Is it something in the sensors, is it heat within the
decoding chip(s), or is it an iPAQ on the way out? As far as I could
tell, it was limited to the screen only - the iPAQ itself was fine.

-John

Darryl Ramm wrote:
All sorts of problems can happen in heat with iPAQs and the touch
screen becoming unresponsive or erratic is fairly common. The best way
to avoid this is to keep sunlight off the PDA while on the ground in
the heat and maybe leave the canopy open if safe to do so. A light
colored cloth covering over the PDA can help but the ultimate is the
Franklin fabrication Platinum canopy cap which keeps the whole cockpit
cool. Failing that replace the PDA.