forget dat stuff, i will completely remove it and then reinstall it to see if that works.
I'll inform you if it does.
Wait, some things:
"InstallFolderFromRegkey: C:\Program Files (x86)\Rockstar Games\Grand Theft Auto IV"
Is that where you installed your game?
Instead of running the install from the .exe, run it from the .msi.
Try moving the whole installer to another place than Desktop, then try again with either the .exe or .msi.