Cannot drag & drop a file

Vista Home Premium
Palm Desktop and Quick Install
Treo 650

For weeks, I could install a file on my Treo by simply
double-clicking on it, which would open the associated
application (Quick Install), place that file in queue, and await
HotSync. Or, I could drag-and-drop the file from wherever onto
the Quick Install window. I then did a Bluetooth hotsync, which
has been working perfectly.


Suddenly, neither will work. The automatic way generates a
"Windows cannot find..." response. Drag generates a circle with
a bar on it. My only recourse is to pull the SD card from the
Treo, slip into the slot on the laptop, and install the file
that way. It works, but...

Everything else on this very nice laptop works fine, and there's
nothing new.

???