Perhaps the driver is redefined under a different name, or that specific driver was removed from the 7-26 version. Have you tried installing your printer as a "new printer" in the 7-26 version?
I'm using version 07-26 and I am unable to add a printer. My previous version 06-06 works fine. Here is the message that I get.
Unable to load the requested driver:
Unable to create the Foomatic driver [HP-LaserJet_5P,ljet4]. Either that driver does not exist, or you don't have the required permissions to perform that operation.
Perhaps the driver is redefined under a different name, or that specific driver was removed from the 7-26 version. Have you tried installing your printer as a "new printer" in the 7-26 version?
I ended up testing the CD. It fails on this computer but OK on another. I burned another CD and it works fine. Burned it at x8. The one that failed was burned at x32. Maybe it had a problem reading the CD. I didn't see any errors the first time I booted up with it.

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