What is the difference between your "Custom" park and the other one? What version of Windows are you using? It's very tough to know what is crashing your park, as there could be many reasons.This thread may help you.http://www.shyguysworld.com/index.php/topic,14639.0.htmlOne possibility for crashes has to do with memory. Since RCT3 was designed to use a maximum of 2GB of memory, playing it on operating systems that uses a lot more can cause problems. Many of my parks crashed when I upgraded from Windows XP to Windows 7. This program stopped the crashes. It's called Large Address Aware. http://www.moddb.com/downloads/large-address-aware1