I was updating Solaris on my W2100z the other night. After applying the latest recommended patches, I rebooted and went off to get a drink.
On my return I was rather startled to find displayed the old message "Invalid system disk. Press any key to continue." Oh bother - what's gone wrong?
It would be a bit of a pain, because I do quite a bit of development on this machine and I really don't want to lose it. The usual suspect in these cases would be a floppy disk, but the W2100z doesn't have one, so I was worried for a second that the main disk had been trashed.
But then I worked out what had happened. I had taken the recommended patch bundle home on a zip disk, and left it connected. So the invalid disk it was complaining about was in fact the one I had left in the USB zip drive. (So clearly the W2100z is capable of booting off a USB device. Scary.)