Symptoms for 10.5.7 with Ati HD4870 (Asus in my case):
-after installing the Natit.pkg everything works fine
-on 2nd reboot you get blank screen
-boot with -x (safemode) and reinstall Natit.pkg
-everything works again...until 2nd reboot when u get blank screen


I know this is happening to other people (from what I read in comments), and they all said they can live with it:)), well...I couldn't.

To fix this annoyance I have prepared a startup script which will run with root (or some root equivalent) credentials and automatically and silently install the Natit.pkg on each boot, to fix the blank screen after 2nd boot.

-create a folder named ATIFix in /Library/StartupItems
-Copy these attached files in there:
ATIFix
StartupParameters.plist

-create a folder ATIFix in /Library
-copy Natit.pkg in there

-Install Natit.pkg and reboot to allow OSX to repair permissions on the StartupItems
-reboot twice to test

Have fun:)

Hey, Are you using the DVI2VGA to connect monitor? I also using a Asus 512M 4870 with two DVI and a S-Video. Not sure what's the problem caused it do not work in the second time.