I keep getting a "not a valid font" error when trying to install fonts that I got from my old XP to my new Windows 7 professional. I have even tried to redownload them and start from scratch. I'm still getting the same error. They are OTF and TTF fonts. I have right clicked and gone into properties and deselected "unblock". I have right clicked and hit install. Double clicked and hit install, and tried just dragging and dropping into the font folder. HELP!

Some older fonts that worked fine on 3.11, 95, 98 and with some exceptions on XP are not recognized by Vista and 7. Almost always the cause is in the naming section, often missing the unique font identifier. But as you are not willing to tell which font(s) you are talking about this is all there is to say about your problem.
See, abstract in, abstract out.