The drive is already mounted when windows starts-up via the login script.
I also used the /persistent:YES option ( mount for every user )
And i also started the nrpe service as the domain admin user.
I'm sure it's a envirnment problem because i altered my script with if not exist and returned the same result.
P-drive doesn't exist, so my script runs perfectly but it can't find mounted drive.
if not exist p:\nagioscheck.txt GOTO :nok
echo "P-drive OK"
echo "P-drive doenst' exist "