after a simple restart last night, my 500 mhz titanium pwrbook will no longer boot up. the white apple screen sit for a long time with that thingy spinning around and then finally it makes it to the blue screen, but right when the "Mac OS X" rectangle pops up, it immediately disapears. then the mouse icon just spins away (the multicolored one to show you its busy) for about five minutes and then the screen is just blue with nothing on it except the mouse, which i can move around. has this happened to anyone before? is it some kind of virus maybe?? also it has 512 ram and all the latest updates as well as a Farallon wireless card ( i don't know if that will matter or not, but you never know) any help will be greatly appreciated! thanks!