Downloaded 4.0 - replaced Old firefox in Applications, (dragged icon into Applications folder though icon had bar through it - should have been a "clue" big mistake, apparently) dragged new icon into toolbar, tried to open it, won't open says "not supported" now i have no Firefox at all. Have Apple Powerbook OS 10.5 - which apparently won't support it? Too bad you don't put "Warning! about this in bold print on same page as download page So how do i get my "old" Firefox back?