You may have to play with the monitor settings once you're in a PAL screenmode. LCDs are a lot less flexible than good ol' CRTs. When used with Amigas, often the LCDs can't detect when a screenmode has changed, or it will autodetect the wrong mode. Either way, the display will be off. Sometimes forcing an auto-adjust on the monitor will clear it up, other times you may need to manually adjust the display settings (position, size, etc.). YMMV, depending on the particular monitor and/or scandoubler you're using.
