... I have no idea what SmartHeap Library is, sorry....
In the "Blade of Darkness" thread they state that the error message is thrown by one of the game's software components called SmartHeap Library. It shows in the window displaying the error. Just because the error message is the same here, doesn't mean it's thrown by the same application, that's why I asked. Check the title of the error window.
Anyway, I'd just try Compatibility Mode, no matter where the error comes from, especially with Win 8.1
Right-click the game's shortcut and select Properties and then go to the Compatibility tab. There you can set the Compatibility Mode for Windows XP (you can also try Win 7 if it doesn't work). Apply the changes and start the game with this shortcut.