Too late for this years 500: I had the same problem of my game crashing
after loading the patch.
Here's a link for a patch that works. You must have Indycar Racing ( I
just loaded Indianapolis) and ICR2 both loaded up.
Go to: http://www.racesimcentral.net/. In the parts department go to achives,
then Indycar II and click on INDY to ICR2 by Gerhard Lingenberg.
Download it to a temp file. The executable will ask for the location of
your two games and will do the rest. There are other patches at the same
location to adjust AI drivers.
Have fun!