The problem with the pitlane
Author : ?
This is a different problem from the problems mentioned above. It is known only from totally new created tracks as the tracks from IA. It seems like the way the CC's enter the pitlane is also coded in the gp2.exe. This means independent  from the track file itself, the CC's have problems to find the way into the pits. It depends on the position where you try to use a track. This is not known from the original tracks from Microprose. If you put one of the new tracks on all positions and watch what happens when the CC's enter the pitlane you can see four different possibilities:
Normal Driving Line

CC's enter the pits as usual. 

Late Reaction 

CC's are able to enter the pits but they drive not the common line, they turn very late to the right (or left). This means they cross a yellow line. This makes normally no problems. 

Early Reaction 

The cars go extremly early on the line what leads into the pits. This can be a problem if you are directly behind a CC because it slows down very early to make a sharp turn. 

CC's can't enter the pilane. Many of them (not all) can't find the entrance or crash against the wall etc.

This means you can't use every track on every position if you want to play a game where the CC's have to pit at least one time. 
If you want to drive hot laps or quickraces only, it doesn't matter.