ALLUSERS property is not 1

I am trying to install 732 miniruntime on top of 721 in Windows XP and get the following error.

“1:ALLUSERS property is not 1 - this MSM cannot be used for a per-user or fallback-to-per-user install”

As I am a mainframe person, I have absolutely no idea what any of this means (ALLUSERS, MSM, per-user, fallback-to-user).

The only reference in the manuals seems to be some sort of override to the install process but there is no option to do this when running the install off the CD.
More info : Sorry, it looks like the original may have be 62 not 72 and may have been a full install rather than a runtime install. Anyway I used the cmd prompt to add /ALLUSERS=2 when running the miniruntime and it installed OK. I think I might uninstall both and start again.