I've been thinking the same as Shane, but didn't want to say it.
Even if you get the system stable after fiddling around, there are still going to be underlying issues that can cause random crashes which will be extremely difficult to track down. This could be due to an older or corrupt DLL file somewhere in the OS, or some registry key which is completely untraceable. So rather than walk on the edge of a viper pit, I suggest reinstalling. When backing up your Trainz-related data, backup your complete User Data folder. This may sound like overkill, but it will ensure you have all your folders and don't miss anything if you pick and choose one thing or another.
John
Even if you get the system stable after fiddling around, there are still going to be underlying issues that can cause random crashes which will be extremely difficult to track down. This could be due to an older or corrupt DLL file somewhere in the OS, or some registry key which is completely untraceable. So rather than walk on the edge of a viper pit, I suggest reinstalling. When backing up your Trainz-related data, backup your complete User Data folder. This may sound like overkill, but it will ensure you have all your folders and don't miss anything if you pick and choose one thing or another.
John