same problem, vista64 poo edition, dx9 installed dx websetup installed. dx 10 installed, all to no avail.
your solution didnt work unfortunately. The dec06 dx files did do something but not what i wanted. I have also disabled UAC and running as admin. and am loading vanilla arma2 thru mod launcher, but it's the same if i just use the normal shortcut.
i have a copy of rainbow6 around here somewhere, going to go dig for it now.
Gav