Wrong state class -- expecting View State exception in Android 1.5 with Custom View

Ah, the problem would have been difficult to diagnose as originally stated.

Turns out that inside my custom view my ProgressBar was named @+id/progress, but when I used the custom view TextProgressBar in my layout I also called the TextProgressBar @+id/progress, resulting in two views with the same id.

Renaming one of them fixed the problem.