I have the same problem in Gutsy with Intel graphic card, identified by Ubuntu as Mobile 945GM/GMS/940GML Express Integrated Graphics. Whenever I change desktop effects to normal or extra, the box appears. This happens also when executing command mentioned by Sebastien.
I have the same problem in Gutsy with Intel graphic card, identified by Ubuntu as Mobile 945GM/GMS/940GML Express Integrated Graphics. Whenever I change desktop effects to normal or extra, the box appears. This happens also when executing command mentioned by Sebastien.