Ok, this worked for me.... Knoppix worked fine from CD, decided to install to HD. The status bar showed an error with IRQ7 about halfway through install. Burned a new CD at 4x, hoping it was the CD. This time booted with the testcd boot option, ie. -- knoppix testcd lang-us -- Had a massive number of errors. So I swapped out the system's 6 year old 20x CD Drive and replaced it with a newer 48x cd drive, installed to HD without a hitch. In my case, it was the drive, or a combination of the drive and media.

I think (at least in my case) that IRQ7 shows up in the errors because it's the printer port. Probably trying to send the errors to the printer that doesn't exist on my machine. The only device on my machine using IRQ7 is the printer port.

Hopefully this is of some use to someone.