The very low video ram could be culprit. rF2 has undergone several graphic updates between both the cars and the tracks so that vRam is consumed rather easily. The NONE and Release Candidate are under rFactor2 on the library screen. Right click on the text set to the left side that says rFactor 2. Then choose properties from the drop-down menu and betas. NONE is the regular, most up to date version of rF2. Release Candidate currently is the same as NONE until they get closer to another quarterly update. Then the Release Candidate offers the latest tech/options etc so that users can stress test items to verify everything works prior to the official launch of a quarterly update.
Here are some options to try.
Reboot windows, do not open any programs like a browser or music etc.
Boot Steam and run the graphic config program. Set the PP to low, verify your screen resolution & refresh rate is correct. Click OK and then go back to the start and launch rF2.
Choose private practice, no computer controlled cars.
Reduce your graphic settings to the Lowest available options.
Choose a track like Silverstone
Try to load that one car and see if you can drive normally.
If you are able to run 1 car alone, then I think your system is simply on the very bottom edge of usability for rF2.