Well, I worked in my computer, with my 40G Ext-3 Partition (For dual-booting goodness). Then, I got a disk full message. A lot of investigation revealed that my .xsession-errors weighs a full 23 Gigs (lot of investigation because its a hidden file). A bit of head(1)ing, tail(1)ing and more(1)ing allowed me to find that 99%+ of the file is a reptition of this:
Code:
X Error: BadWindow (invalid Window parameter) 3     
  Major opcode: 15 (X_QueryTree)                    
  Resource id:  0x141121c
Naturally, $ cat /dev/null > ~/.xsession-errors helps but I want to fully solve this problem.

KDE on a fully-upgraded i386/Debian Squeeze. Any more info?

EDIT: Also, just by Ctrl-Alt-1+Ctrl-Alt-7 it produces this
Code:
X Error: XSyncBadAlarm 152
  Extension:    143 (Uknown extension)
  Minor opcode: 11 (Unknown request)
  Resource id:  0x0