Comment 3 for bug 458524

I'm experiencing the same issue, on Karmic-rc-server-amd64. However, I think I can add some additional info to shed some light on this:

A thread on the Debian bugtracker mentions that this may be related to a broken libcwidget3. Updating it with 'aptitude update; aptitude upgrade' does not fix it as of post time.

However, I've noticed that the issue may not be with aptitude at all, but with the terminal. Scrolling the bash history on the ttys sometimes prints control characters instead of acting as up/down arrows. If I log in via ssh, aptitude works fine. Based on that, I think that the culprit is more likely the framebuffer device.