fastcgi incomplete headers issues

[raphael]

do you have any security tool around?
does
# usermod -s vu2000
help?
what is the output of grep ^vu2000 /etc/passwd?
by the way, I don't think you used
strace -u vu2000 /var/www/fcgi/master/php5-fcgi-starter
to get a strace, did you? it's output would be cleaner than using strace sudo -u /...
Anyway please try using strace -u vu2000, the first line of its output should be execve("/var/www/....