Hi, I just upgraded to the new version and the behaviour is the same. I updated the bug description. Please see exact steps to reproduce below. Error message still:

The program 'Banshee' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadMatch (invalid parameter attributes)'.
  (Details: serial 22997 error_code 8 request_code 70 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.)

With Wikipedia plugin enabled (which is by default) changing to "Now Playing" view. Mhm, these are ogg-files, which I play. Cover fetching works fine though for the browser view. Nothing related to that, I guess.

$ dpkg -l banshee

ii banshee 1.9.4-1ubuntu1 Media Management and Playback application

I tried now with ALL plugins disabled, and only Wikipedia plugin enabled. It crashes.
With all plugins enabled, but Wikipedia plugin not enabled it does not crash on the "now playing" view.

IMPORTANT to reproduce:
Please keep in mind, to activate the Wikipedia plugin in the Preferences dialog. Then fully exit Banshee (Strg+Q, not just in the tray, exit the program completely) then restart Banshee. Start a song or music track, change to "Now Playing view" then it crashes.


Steps to reproduce:
1) Click on "Now Playing" on the browser list at the left side. This should give you a nice view on the cover.
2) it crashes and gives at last an X error (X Window System error, see bottom log)