If you keep your CONFIG script, PROCESS script and INI file in the same folder you can make things a little more simple and use the built-in macro @SCRIPTDIR to determine the location:
 Code:
CLS
'Send mail to: ' Gets $MailUser ?
' Mail Server: ' Gets $MailServer ?
$ = WriteProfileString(@SCRIPTDIR+'\checkdisk.ini', 'COMMON', 'MailUser', $MailUser)
$ = WriteProfileString(@SCRIPTDIR+'\checkdisk.ini', 'COMMON', 'MailServer', $MailServer)

@SCRIPTDIR is populated automatically with the path to the directory that the script is run from, so saves you the effort of setting an environment variable.