Thanks for your suggestions Martin. I tried following them, but without success. It turned out that the compiz package was indeed not installed, but after installing it and restarting there was no change in behaviour. I also tried removing the ~/.gonf/desktop/gnome/session/ directory and setting System>Preferences>Appearances>Visual Effects to None, again with no change.
More information which may or may not be useful: I should point out that generally my workaround is just restarting compiz each time I boot (i.e. $ compiz --replace &) without having to restart metacity (although occasionally I have to restart both). And when I restart compiz I always get the following error message in my terminal: r...@mobile:~$ compiz --replace & [1] 1636 r...@mobile:~$ WARNING: Application calling GLX 1.3 function "glXCreatePixmap" when GLX 1.3 is not supported! This is an application bug! Starting gtk-window-decorator compiz (cube) - Warn: Failed to load slide: /usr/share/gdm/themes/Human/ubuntu.png r...@mobile:~$ WARNING: Application calling GLX 1.3 function "glXDestroyPixmap" when GLX 1.3 is not supported! This is an application bug! Also, when I display System>Preferences>Appearance>Visual Effects none of the options are actually selected after I restart compiz, even though the effects are working (e.g. the desktop cube). And when I check the /var/log/syslog to find anything related to 'compiz' I get the following (not sure if it's related or not): May 20 13:54:07 mobile gnome-session[1260]: WARNING: Could not launch application '10d41a48d430b8bdae126393718011413500000015010028.desktop': Unable to start application: Failed to execute child process "/usr/bin/compiz.real" (No such file or directory) compiz version: $ apt-cache policy compiz compiz: Installed: 1:0.8.4-0ubuntu15 Candidate: 1:0.8.4-0ubuntu15 Version table: *** 1:0.8.4-0ubuntu15 0 500 http://ca.archive.ubuntu.com/ubuntu/ lucid/main Packages 100 /var/lib/dpkg/status metacity version: $ apt-cache policy metacity metacity: Installed: 1:2.30.1-0ubuntu1 Candidate: 1:2.30.1-0ubuntu1 Version table: *** 1:2.30.1-0ubuntu1 0 500 http://ca.archive.ubuntu.com/ubuntu/ lucid/main Packages 100 /var/lib/dpkg/status graphics controller: $ lspci ... 00:02.0 VGA compatible controller: Intel Corporation Mobile 945GME Express Integrated Graphics Controller (rev 03) 00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03) ... -- metacity and compiz aren't working properly at startup https://bugs.launchpad.net/bugs/543097 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs