One of the 'fun' things about shell themeing is that if, or rather, WHEN you are in the middle of converting a theme from one standard[ish] LiteSTEP format that you are used-to, to the OTS standard, 'things' can go wrong....

There you are, staring at a 'stuck' cursor, waiting for the theme to load...there's a thrashing of drive action, but nothing happens....
Ctrl-Shift-Esc and you discover that litestep.exe is zipping along merrily at 100% cpu and 650 meg of ram....now THAT'S LIGHT...
You kill the process, and ShellON pops up to get you reloaded, while you do the 'right thing'[tm] and comment out various module lines in the step until all that's left is a popup and a desktop.....STILL no luck.
Hmmm...curiouser and curiouser...
You pop your head back into the images folder and....where's a4.png...otherwise known as the 'PopupBottomPix'?
It's conspicuous by its absence.
You deftly comment out one line in the step , et, voila!
One missing image and your whole shell can be fragged.
I've been using LiteSTEP exclusively for over 5 years.....and STILL screw up.
[Damn I must be thick]....