Hey guys thanks for the replies!
The problem seems to occur on both old and new computers, but mainly the older ones.
Yes, they're in the same OU and yes, I've had a tech logged in as a domain admin while doing gpupdate /force. I'll try the ipconfig /flushdns
I've disabled the slow link detection, so I don't think slow connections would be causing the problem... not sure though. I'll try loading the script via AD
All MSI packages deploy fine. In fact, I think all computer settings apply to all computers, but the user settings (where i have the logon script) doesn't get applied to some.
Thanks guys