have had problems in the past (Jan 07) getting ARD to work when Catalyst is in full screen mode (ie HUD). (G5's not Intels)
simon - i thought in the past you have used various dodgy flavours of vnc - maybe it is these that caused your problems?

Maybe you didnt uninstall them properly-
you definetly had dodgy vnc clients-
maybe you had mixed versions of client and servers. everything should be up to 3.1 now.

ARD gets its info from the Desktop GUI not from the 3D engine on the graphics card. Unless this has changed since I came across this problem - then the screen will not update correctly when Catalyst is in full screen mode. (will work fine on desktop mode) Unless I missed some major settings.....
this is not true.
dont know where you heard "ARD gets its info from the Desktop GUI" its all one 3d world baby....

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there arent any settings-
i have never had any problems.

i use remote desktop all the time - i havent seen any issues like this.