ATI display drivers install failure

Shortly I sometimes get error in log, when instaling these drivers, that write in bottom "you have to be in admin group" or just installation failure. It doesnt always happens though (I've been messing with reinstalling OS alot lately so I did it alot). I'm not sure but it may accuring only when I install hotfixes. Does it make sense? Like these drivers not approved by MS or something?
Generally I know how to install them in unusual way, ei uninstall old driver, and run setup as administrator with right click menu (or just login as admin maybe). But I wonder why it simply doesnt work like always...
Also after I uninstalled old 8.10, and ran 8.10 2nd hotfix as admin, in middle of install I was asked whether I accept to install this driver, and a checkbox "always accept from this.. publisher?" something like that. I think that means its not allowed in vista by default. I thought MS and AMD/ATI partners...