Wanted to post an error I repeatedly got in case anyone else out there has the same issue. Went to do a snowleopard (10.6) upgrade and clean install on a mac pro (coming from 10.5). After about the "26 minutes left" mark I repeatedly got the following error:
"install failed mac os x could not be installed on your computer the installer could not copy the necessary support files click restart to restart your computer and try installing again"
i searched a bunch for this and could not find any definitive answers or help. the log file was very vague, referring to errors writing package(s).
at first i thought it was a bad DVD drive as it was making a bunch of noise and taking a long time to boot. So i went and purchased a new DVD drive and successfully installed it. nope, same issue. then i pulled out all of my 3rd party RAM. nope. then i tried swapping the RAM into different configurations, nope.
after many many hours of various methods and re-partitioning, etc, just for the heck of it i replaced the harddrive, and it worked!
So, for those of you out there who get this error, try troubleshooting your hardware, try swapping your harddrive.