SDK stands for Software Development Kit.

It is for people who want to make dynamic dreams using C++.  The effects SDK is included with Deskscapes simply because it always has been and lets you create new effects in C++.  You can also create new effects using simple pixel shaders which is what the bulk of the effects are in Deskscapes.

If you are not a software developer you do not need to worry about it.

Every day is every 24 hours, or every time you login.

Hey amigo!  After much trial and error, I have narrowed the bug down for ya.  8)

In the latest Deskscapes rev, the problem ONLY occurs in the Photodream dream when "Move picture in three dimensions" is Enabled and only on Nvidia graphics cards.  It just so happens that this is my default hardware/dream configuration for every monitor I own, haha.

The background refresh/redraw disappears entirely (it is not drawn or redrawn) and the animated picture moves for about one second, leaving a trail artifact behind, before it just freezes.

This does not happen if any of these conditions are not met.  

I hope that helps you narrow it down to a specific line of code.