I get a white projectm window in amarok and mythmusic in gutsy backports with :
libvisual-projectm 1.0-1~gutsy1
libprojectm1 1.01-3~gutsy1

I don't know if it is related but in mythmusic if projectm is the default visualization plugin I get the white window, but if I cycle the plugins, when projectm is selected again I get a floating point exception with the following trace:

Program received signal SIGFPE, Arithmetic exception.
[Switching to Thread -1261446304 (LWP 12313)]
0xaad99f29 in SOIL_internal_create_OGL_texture () from /usr/lib/libprojectM.so.1
(gdb) bt
#0  0xaad99f29 in SOIL_internal_create_OGL_texture () from /usr/lib/libprojectM.so.1
#1  0xaad98b90 in SOIL_load_OGL_texture_from_memory () from /usr/lib/libprojectM.so.1
#2  0xaad951ea in TextureManager::TextureManager () from /usr/lib/libprojectM.so.1
#3  0xaad8ba7c in Renderer::Renderer () from /usr/lib/libprojectM.so.1
#4  0xaad58791 in projectM::projectM_init () from /usr/lib/libprojectM.so.1
#5  0xaad5a47c in projectM::readConfig () from /usr/lib/libprojectM.so.1
#6  0xaad5b456 in projectM::projectM () from /usr/lib/libprojectM.so.1
#7  0xaafa793b in lv_projectm_init () from /usr/lib/libvisual-0.4/actor/libprojectM_libvisual.so
#8  0xb244c6ac in visual_plugin_realize () from /usr/lib/libvisual-0.4.so.0
#9  0xb2446cd8 in visual_actor_realize () from /usr/lib/libvisual-0.4.so.0
#10 0xb244ac1d in visual_bin_realize () from /usr/lib/libvisual-0.4.so.0
#11 0xafab04b0 in LibVisualPlugin::switchToPlugin () from /usr/lib/mythtv/plugins/libmythmusic.so
#12 0xafab169e in LibVisualPlugin::LibVisualPlugin () from /usr/lib/mythtv/plugins/libmythmusic.so
#13 0xafab1af8 in LibVisualFactory::create () from /usr/lib/mythtv/plugins/libmythmusic.so
#14 0xaf9d971a in MainVisual::setVisual () from /usr/lib/mythtv/plugins/libmythmusic.so
#15 0xaf9f4fb2 in PlaybackBoxMusic::CycleVisualizer () from /usr/lib/mythtv/plugins/libmythmusic.so
#16 0xaf9faeab in PlaybackBoxMusic::keyPressEvent () from /usr/lib/mythtv/plugins/libmythmusic.so
#17 0xb62838a3 in QWidget::event () from /usr/lib/libqt-mt.so.3
#18 0xb61e3af0 in QApplication::internalNotify () from /usr/lib/libqt-mt.so.3
#19 0xb61e5ac0 in QApplication::notify () from /usr/lib/libqt-mt.so.3
#20 0xb617627d in QApplication::sendSpontaneousEvent () from /usr/lib/libqt-mt.so.3
#21 0xb6166c69 in QETWidget::translateKeyEvent () from /usr/lib/libqt-mt.so.3
#22 0xb617304f in QApplication::x11ProcessEvent () from /usr/lib/libqt-mt.so.3
#23 0xb618a1a4 in QEventLoop::processEvents () from /usr/lib/libqt-mt.so.3
#24 0xb61fe1ce in QEventLoop::enterLoop () from /usr/lib/libqt-mt.so.3
#25 0xb6bead27 in MythDialog::exec () from /usr/lib/libmyth-0.21.so.0
#26 0xaf9d0022 in startPlayback () from /usr/lib/mythtv/plugins/libmythmusic.so
#27 0xaf9d213a in runMusicPlayback () from /usr/lib/mythtv/plugins/libmythmusic.so
#28 0xb6a53775 in MythMainWindow::ExitToMainMenu () from /usr/lib/libmythui-0.21.so.0
#29 0xb6a53c56 in MythMainWindow::customEvent () from /usr/lib/libmythui-0.21.so.0
#30 0xb624bf95 in QObject::event () from /usr/lib/libqt-mt.so.3
#31 0xb62835b3 in QWidget::event () from /usr/lib/libqt-mt.so.3
#32 0xb61e3af0 in QApplication::internalNotify () from /usr/lib/libqt-mt.so.3
#33 0xb61e64ba in QApplication::notify () from /usr/lib/libqt-mt.so.3
#34 0xb6176209 in QApplication::sendEvent () from /usr/lib/libqt-mt.so.3
#35 0xb61e4b28 in QApplication::sendPostedEvents () from /usr/lib/libqt-mt.so.3
#36 0xb61e4c30 in QApplication::sendPostedEvents () from /usr/lib/libqt-mt.so.3
#37 0xb618a215 in QEventLoop::processEvents () from /usr/lib/libqt-mt.so.3
#38 0xb61fe1ce in QEventLoop::enterLoop () from /usr/lib/libqt-mt.so.3
#39 0xb61fdfde in QEventLoop::exec () from /usr/lib/libqt-mt.so.3
#40 0xb61e5699 in QApplication::exec () from /usr/lib/libqt-mt.so.3
#41 0x0806a924 in ?? ()
#42 0xb5a83050 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#43 0x08061361 in ?? ()