LilyPond Problem -- won't load

[Aaron]

Hi!

I used lilypond for a while a few months ago, loved it, and then simply took a

break from composing. When I came back, lo and behold, projects that used to

compile fine with lilypond didn't work. LilyPond didn't even load when I

right-clicked and selected "Generate PDF". When I looked at running processes,

it shows lilypond-windows as running, using 15MB or so of memory, but nothing

happens that I can see. I upgraded, didn't fix it. Uninstalled and 

re-installed,

didn't fix it. The examples that shipped with lilypond didn't compile 

to PDF either.

Any ideas? I'm totally stumped, and frankly, a bit disappointed.