Yesterday one of my friends called up and he was getting the below issue and was unable to create a new custom list or a list from a list template.
Object reference not set to an instance of an object. at ASP._layouts_new_aspx.OnLoad(EventArgs e) in c:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\new.aspx:line 23
He was able to create it however on dev / test / stage boxes but not on production.
Guess what??? the only difference was, production is on https.
Fix: Create the list on extended web site (Intranet) instead of creating on the public facing domain on https.