my Powerbook has been acting strange lately and it seems to be getting worse... about 3 weeks ago, my harddrive failed. this happened after about a 2 day period where my machine was acting sluggish, unbearably sluggish at some points, and then it finally bit the dust. i got it replaced, expecting it to fix the problem. nowadays, i'm not 100% sure that a new drive DID fix the problem (clean install and everything), as i've been seeing some signs that my laptop (when perfectly healthy) never exhibited. for example, in the past 12 hours, i've gotten the gray 'you must restart your computer screen.' after the first time this happened, i deleted the new fonts i recently installed. yet it happened again. and again. is my computer sending me some warning signs that i can act upon?