[Problem]
The game behaves weird, and runs way too fast. Everything appears to be in uberturbo mode. Graphical Artifacts everywhere, and the AI messes up because of the high speed and keeps ramming things randomly.
[Solution]
Known problem on Dual Core CPU's. After starting the game, task out, open the task manager, and set the CPU Affinity of the GTA:SA thread to only use one CPU. Task back in, and it should work normally.