Hello, this is my first post on these forums...so here goes:
I bought the DVD version of GTA IV

and
dual-boot into
Windows on my Mac so that I can play. I installed the game onto a USB hard disk, in XP compatibility mode, and the game starts fine. But as soon as I begin playing, I notice that the textures of the buildings and roads (but not cars, streetlights, dumpsters, and people) are all invisible

.
In the graphics settings, it claims I've used 275/60 MB (complete garbage since I have 384 MB). I also can't change any of the settings; they are locked.
My Mac meets the minimum requirements, although it uses the Intel HD 3000 graphics (with a minimum of 384 MB allocated for graphics). However, others have run this (
Youtube) on my exact computer, so I know it is possible to run this game on my system. I don't care about running this on anything higher than minimum settings, just so everybody understands...
I did my research before posting. I tried commandline.txt, I tried putting the command line options in the target of a shortcut to LaunchGTAIV.exe, and I tried deleting settings.cfg. Nothing had any effect.
What did I do wrong? (And, no, my mistake was not trying to run this game on a MacBook Pro.)