Kiitos vinkeistä, vaikka kumpikaan ei muuttanut tilannetta. Asensin myös seamonkeyn, joka myös antaa virheilmoituksen
viihde@viihde-desktop:~$ seamonkey
The program 'seamonkey-2.0-bin' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadLength (poly request too large or internal Xlib length erro'.
(Details: serial 692 error_code 16 request_code 128 minor_code 4)
(Note to programmers: normally, X errors are reported asynchronously;
that is, you will receive the error a while after causing it.
To debug your program, run it with the --sync command line
option to change this behavior. You can then get a meaningful
backtrace from your debugger if you break on the gdk_x_error() function.)