Failed install via Group Policy

[ecold]

I have some installations by Group Policy that do not install. I have a requirement as Windows Installer 3.1. If a PC does not have that, what happens with the GP? How do i know that it failed to meet the requirements. Also, almost all PCs should have 3.1 because I rolled it out via SUS/WSUS before Service Pack 2 of XP came out. Does w2k use 3.1 and might that be why some of them do not have it as well as some XP SP1? Most that I have looked at have SP2 of XP but didn't get the install. All other GPO's are applied. Office XP SP3 is the version that seems to be having trouble but some do and some don't. Any clues to check for would be appreciated. Also, those manually installed do not always work others, work flawlessly. I realize we could be talking a number of varibles but I really don't know where to start other than the obvious, patches.

Thanks for all the help!!