Thanks for reporting the problem (the theme site parser doesn't detect it, and I haven't yet updated to 3.10), I'm away and I won't be able to properly check/fix my themes until a couple weeks, but it seems that the problem might be that those themes have touchscreen commands, and there was a relatively recent touchscreen commands syntax change.
I had in mind that the iPod video would ignore any tocuhscreen areas commands (even if they were wrong), but apparently that isn't the case, or that changed somewhere near release 3.10 (could someone please confirm this?) If those aren't ignored, any touchscreen commands syntax change breaks the themes not only for touchscreen targets (in this case the Cowon D2) which is logic, but also for non touchscreen targets (in this case iPod video).
In the meantime, it seems that removing the touchscreen commands from the theme files fixes the issue. Since I make all the 320x240 themes really for the iPod video, I place all the touchscreen commands together, both in the .sbs and .wps files, so it should be relatively easy to find them and delete them (all the lines beginning with %T( if I remember correctly. I will update them later gradually.