Having problems getting GTA IV to run on your PC? Rockstar have uploaded a few documents to their GTA IV support page
This GTA IV error codes
document explains all the common errors such as the MMA10
error, and how to fix them. To get rid of MMA10, you can sign out of Social Club as a temporary fix.
Another document explains each graphics setting
in GTA IV, you may wish to read about this if you want to make the game look better, or if it's running too jerky, reduce some of the settings that will help it run smoother.
We expect Rockstar will soon release a patch to fix the common problems people are finding, but until then you have these documents and of course our forums
for general support.