Updates won’t apply – installer just stops at “locating relocatable files”

We can't apply the 10.4.9 Update. I've seen this happen on 3 Tiger servers now with other updates too. The installer installs the admin tools, etc... when it gets to the actual OS update it hangs at "locating relocatable files" (which can only be seen in the installer log). The GUI stops at "Configuring installation". No error messages. No freezing. No feedback at all. Just nothing. Have to force quit the update. I previously got the update to run by extracting it from the mpkg and taking out the VolumeCheck script. This isn't working this time. If I manually run the OS update the VolumeCheck says that no volumes are suitable for installation. This doesn't make any sense. (Automatic) Software Update fails too. Help!