firefox uses disk very intensively

[Konstantin Novichyonok]

I was using FF (of course, with some apps run in background, but actually they were only waiting), when suddenly performance dropped down, I saw 'hard disk usage' light flashing permanently. I even couldn't log in from terminal (tty1) -- so terrible performance it was.
So I did hard-reset and then searched for files have being modified about that time (unfortunately, I cannot determine the moment of actual start -- however, I concluded it from amount of files: if system hangs, less files are been modified, right?).
Output is in attachment.
________________________My humble analysis___________________________________________
All files about pam and login are because of my unsuccessful attempt to login via console.
Files of fonts and icons present because I tried to return to X -- however, less than a half of desktop was painted.
The most suspicious file is /home/knovich/.mozilla/firefox/fppelyph.default/GoogleToolbarData/dict.dat
What are ideas?

PS Sorry for clumsy report & pour English :-[