Couple of questions: a) how did you install KDE - dual boot method or .deb? b) do you have swap enabled? you'll need swap to run things smoothly. c)what are you doing in KDE when this line appears on your screen? d) what machine are you running? if it's a N810 and you're installing KDE on your internal card - there's a thread about how to tell if your internal card is corrupted I've never had problems with KDE so these are all just educated guesses