Getting undefined index: base_theme_url in my error log

[winky100]

I am getting the following error in my error logl. Does anyone know a fix for this?

8:Undefined index: base_theme_url
File: Source/Load.php
Line: 1952

SMF 2.0-RC5

[Chas Large]

Sorry for the delay in responding. Can you tell me what theme your forum is defaulted to? Is it the SMF default or a new theme you have installed?