Shift+pgup to scroll up.
Sounds like you need to run xf86config or xf86cfg or something. (I never can remember what the damn things are called.) Your monitor and X aren't getting along.
If you've got a reasonably recent monitor (VESA 2+) try enabling framebuffer support. Need more details and I suck with monitors and X configuration, anyway.
Good luck, though. Slack's great when you get there.
-- Argh. This is like the 5th time today I've posted something right after it's already been said. Gonna change my LQ name to Redundancy Check.