Zquest crashes whenever <none> on the item screen is selected. Unfortunately, With this occurring I would not be able to have items like keys. but I can have 4 shop types, and am able to use the special items. It may be compatibility issues because I am using Windows 8.
Zquest item bug.
If you're referring to the crash related to selecting a screen item, then this bug has been fixed since 2.50.1 RC1. But make sure you download the latest build, which is 2.50.1 RC2.