GTK applications fail to start - xfs restart needed Options

After a recent update (Xorg was updated among other things), GTK apps stopped running in my kde4. I have a Debian unstable, updated around 22 April. When I try to run them I get the following error:

ga@grzes:~$ iceweasel 
The program 'firefox-bin' received an X Window System error. 
This probably reflects a bug in the program. 
The error was 'BadName (named color or font does not exist)'. 
  (Details: serial 888 error_code 15 request_code 45 minor_code 0) 
  (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.) 
ga@grzes:~$ gimp The program 'gimp' received an X Window 
System error. 
This probably reflects a bug in the program. 
The error was 'BadName (named color or font does not exist)'. 
  (Details: serial 6955 error_code 15 request_code 45 minor_code 0) 
  (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.) 


(script-fu:4643): LibGimpBase-WARNING **: script-fu: gimp_wire_read(): 
error

I have to restart the font server manually to have it fixed:

ga@grzes:~$ su 
Password: 
grzes:/home/ga# /etc/init.d/xfs restart 
Stopping X font server: xfs. 
Setting up X font server socket directory /tmp/.font-unix...done. 
Starting X font server: xfs.

Any ideas what could be wrong? Is it a configuration issue? My system has been updated for the last 7 years, so I can have some old settings.

EDIT: I would be grateful if someone could point me to a relevant discussion list or bugzilla site, because I am stuck with this problem.