bizarre console problem

[settimio di cori <mino59@mindspring.com>]

I'm running debian unstable, kernel 2.4.2, latest kde packages.

>From the moment the kdm logon screen appears and at any point thereafter
(i.e. when kde is running), if I switch to a text console (alt-ctrl-F1
etc.) the screen is filled with vertical black and white stripes and I
cannot see any text characters. Commands appear to work - if I type
"shutdown -h 0" it actually works, even though I cannot see any of the
characters I am typing.

While the system is booting everything looks fine - the problem seems to
begin only after the kde logon screen appears.

Any ideas??? Have I accidentally deleted an essential package or
corrupted an essential file???

Thank you,

Mino