roScreen, screen saver and Roku 2

I hope I'm doing something wrong, but if I have an roScreen open and the screen saver kicks in the screen basically is frozen once the screen saver is dismissed. The code still appears to be operating properly, but no updates appear on the screen. On a 1st generation unit everything works just fine (including getting the screen saver to display instead of just a blank screen). Here's some basic code that illustrates the problem:

Sub RunUserInterface()
    screenFacade = CreateObject("roPosterScreen")
    screenFacade.showMessage("")
    screenFacade.show()
    port = CreateObject("roMessagePort")
    screenFacade.SetMessagePort(port)

    di = CreateObject("roDeviceInfo")
    m.dsize = di.GetDisplaySize()
    if m.dsize.w = 1280 then
        m.screen = CreateObject("roScreen")
    else
        m.screen = CreateObject("roScreen",false,640,480)
    end if
    if type(m.screen) <> "roScreen"
        print "Unable to open screen"
        return
    end if

    m.screen.SetPort(port)
    m.screen.SetAlphaEnable(true)
    m.screen.Clear(&h108010FF)
    m.screen.Finish()

    m.compositor = CreateObject("roCompositor")
    m.compositor.SetDrawTo(m.screen, &h108010FF)

    bm = CreateObject("roBitmap", {width:50, height:50, AlphaEnable:true})
    bm.Clear(&h801010FF)
    region = CreateObject("roRegion",bm,0,0,bm.GetWidth(),bm.GetHeight())
    sprite = m.compositor.NewSprite(0,0,region)
    print type(sprite)

    while true
        msg = wait(1000,port)
        print "Moving..."
        sprite.MoveTo(rnd(m.dsize.w-bm.GetWidth()),rnd(m.dsize.h-bm.GetHeight()))
        m.compositor.Draw()
        m.screen.Finish()
    end while
End Sub

-JT