Well, I was able to install the Orchestral Strings I library by copying the disc contents onto a hard drive, downloading the new Library Installer 1.02 and installing it from the hard drive.
Since I can successfully read from the drive to write to the hard drive (just copying the data, not actually installing) I'm assuming it's not the drive or the wires. Like you, I don't think the problem is with the dvds, I'm pretty sure it's something weird with my system.
I'll have a little time on Sunday, but much more on Monday to deal with this. I may still end up reinstalling the OS, it's still touchy about some other stuff. If so, I'll try installing it via the regular method to see if the OS install fixed anything.
Oh, and just to answer the questions, 10.4.4 and yes, I've tried different ownership on the hard drives, and checking 'Ignore ownership on this drive.' Neither worked. The drive was formatted in Mac OS Extended. I will run TechTool soon to check my drives, though I fixed some stuff about three or four weeks ago and all was fine after that. I've put a copy of my system profile here:
(link removed, as was the file)
if you're still interested in investigating this. I'll leave that up for a few days.
Thank you for all your help on this. Your suggestions helped me come up with the workaround. Have a great week!
-Helen