Canon RAW & Win Explorer (similar to Nikon problem)

I'm having a similar problem to that described here by Nikon RAW users.

Problem: - Vista Home Prem, release edition
I open Windows Explorer and navigate around quite happily until I reach
a sub-folder of "Pictures" (containing .jpgs converted from RAW files)
which itself has a sub-folder with files of type .CR2 (from a Canon
400D). WE then terminates with an error message. A number of photo
manipulation programs do the same, presumably because they are calling
the same routines.

Or that used to be the behaviour - since I installed the Canon RAW codec
the other day, the same action causes the machine to freeze completely
(sometimes, though not always), not even responding to a "three-finger
salute".

Anyone any idea what's going wrong? It's putting a bit of a cramp in
the manipulation of my RAW files, which was the main reason for
"upgrading" my m/c ;-)

DaveP