First, sorry for my english... (I'm French)
I try to start gephi 07.beta on Vista, and as some people here, (on Seven), it doesn't work.
After reading one topic where it was say to check the message.log file in C:\Users\XXXXXXX\AppData\Roaming\.gephidesktop\dev\var\log, I try to find it but don't find the directory.
So I open the gephi07beta.conf (\Gephi-0.7\etc), and I see this line default_userdir="${HOME}/.${APPNAME}/dev"
I replace ${HOME}/.${APPNAME}/dev by a directory I made.
And, Gephi launch correctly
P.S (Maybe it's the dot of .gephidesktop who make the problem ???)