I don't know if anyone knows how to fix this, but recently I had to reinstall my copy of windows. After installing the driver for my sound card, suddenly my taskbar disappeared. It seems it is still down there (tweaking the settings sometimes shows a HINT of it that I can right click on), but nothing I do will make it come back to normal.
Thanks, works great. The new preview version of Opera does support gmail pretty well, not perfect yet but I'm sure it will be closer eventually. But the browser itself is pretty unstable at this point.