After a lot of days without this problem, it happened again today. You can mark the bug as found in the current version in sid :-)
It happens more often when I have a programme of scientific computation running in background. This programme does not consume much RAM (0.1 %) but consumes a lot of CPU (90 % at least, usually 99.7 %). Regarding gdb, I am afraid I cannot login from another computer. I tried Ctrl + Alt + F1 and run gdb as root, but gdb seems to freeze (goes to a new line and stays there forever and ever). Thank you.
