Here's another thought: When you booted from the installation disk, was that the same OS version as the one that's installed? If you used, for example, a 10.5 disk to repair a 10.6 system, the version of Disk Utility will not be correct.

Just asking.

Jon

macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365