Vista vs. Palm Quick Install -- I need a guru!!!

Palm OS 5.x, Treo 650
Windows Vista Home Premium
Core Duo Laptop


Palm software worked perfectly on this Vista laptop, with fast
Bluetooth HotSync and no problems at all, but suddenly:

Cannot drag & drop a .prc file from desktop to the Quick Install
display. I get a circle with diagonal bar.

When I double-click any .prc file on the desktop, I get "Windows
cannot find (then it names the file and the correct location).
Be sure you typed it correctly..."

The association of prc and pdb files with Quick Install is correct.

There appear to be no other problems. And for those familiar
with Vista, problem persists with UAC off.

I can stick the SD card into the laptop's cardreader slot and
put books, music, etc. into the proper folders on the card.
However, I cannot properly INSTALL anything!!!

Help!