Loading a program update (Adobe) error on dual boot

[clanofwolves]

I have my hard drive partitioned so I can dual Vista Ultimate and XP Pro. When I logged into the D: partition which has XP loaded, is the default OS and where I installed my Adobe Acrobat 7.0, it asks to install updates and I accept; the 7.1 update downloads and starts, but I get error 1303: "the installer has insufficient privileges to access this directory D:\Windows\winsxs\Policies." I've done some digging in Adobe's knowledge base and it says to modify the permissions for that folder. I guess that makes sense, but it shouldn't be trying to install anything on the C: partition but rather the D: where the program is installed... right? Since I'm installing and update, it doesn't give me ANY option about where to install the files.

I've searched the registry for a setting that points to D: instead of C: but found nothing.

Anyone have any help???