MY COMPLETE REPLY:
Thanks for your suggestions!!!!! I tried using the Mint 11 disk on my Sony laptop without installing it: it worked! Eventually I installed Mint 11 permanently onto the Sony's hard drive and I now have a dual boot laptop that works perfectly. CONCLUSION: The Mint 11 DVD was NOT defective.
I again attempted to install Mint 11 and later, with the same bad results, Ubuntu 11.04, onto the older HP Pavillion laptop. They both installed but would not boot.
After much messing around with the HP Pavillion the following message appeared on the screen in red (and I was starting to see red!): "40.688042 AC'97 1 access is not valid [oxrrrrrrrr]removing mixer, [40.688120] ali mixer 1 creating error." I hope this means something to somebody. . . . .
I do not think the old HP is up to either Mint 11 or Ubuntu 11.04.
Does anyone have a suggestion about where I can find some Linux variety (and which Linux variety and where might I find it?) that might be compatible with my older HP Pavillion ze4125 laptop computer?