Yes. Provided the d: drive is formatted you can put files on it, including executables. There are people who use the c: for system software only, and d: to install their applications.
You can even run programs from drives located on a networked computer, provided all needed dll'a are either in the folder they reside in, or in your own windows\system-folder.
No. Fonts are installed in c:\windows\fonts. It could well be you reached a maximum there, so you would have to uninstall some fonts before installing new ones. It might help to quote the exact error message to get more help on the subject. Or look it up on google yourself.
Hope this helps.
My computer came with a "built in partition". It's called "D". My problem is that I have 1350 fonts on my "C" drive. The latest software I installed on "C"
won't download the fonts that came with it; no more font space? So can I run this software from "D". I don't know if the drive is primary or extended, and it was not set up with "Partition Magic" or any other partioning software. HELP! Thanks!