A -108 error generally means Peak doesn't have enough RAM. If the installer gives you this error, increase the installer's RAM in the Finder's Get Info Window.
If Peak gives you this error, set Peak's application RAM in the Finder's Get Info window to approximately 500K less than the total free RAM reported in the "About This Macintosh" window in the Finder's Apple menu. If you've already done this, see the next paragraph.