Bem pensado Nabais, vou fazer isso e depois partilho com vocês a informação, caso obtenha algum erro nos logs. Obrigado!
EDIT:
Ok, ao correr o compiz pelo terminal fui surpreendido com o que apareceu.
Código:
hash@hal9000:~$ compiz --replace
/usr/bin/compiz.real (core) - Warn: Unable to parse XML metadata from file "ccp.xml"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
A handler is already registered for the path starting with path[0] = "org"
inotify_add_watch: No such file or directory
/usr/bin/compiz.real (cube) - Warn: Failed to load slide:
Aqui nem corri o emerald pra tentar simplificar, mas obviamente alguma coisa não está bem aqui. Apesar das mensagens de erro, o compiz parece estar a funcionar, mas se começar a usar vários efeitos, ele reinicia a sessão sem qq aviso.
EDIT2:
Bem, tive a googlar e descobri aqui
http://ubuntuforums.org/showthread.php?p=3314156 uma possivel solução que seria alterar o backend do compiz. Eu realmente andei lá a mexer e tinha alterado para a 2ª opção. Voltei pró "flat" e aparentemente já não crasha, embora os erros ao iniciar o compiz pelo terminal permaneçam.
Agradeço ao Nabais por me ter apontado na direcção correcta, apesar de ainda não estar 100% convencido que isto está como deve ser. Acho que estes últimos updates do compiz tornaram-no mais instável do que estava anteriormente. Espero que para a próxima versão estas questões de estabilidade já estejam resolvidas.
EDIT3:
O X já n crasha, mas agora tou com problemas de refrescamento da imagem... Cada vez que abro uma janela, tenho que a fechar e voltar a abrir para ver o que ela lá tem. Com o outro backend n tinha este problema, mas o X crashava :|
Já não sei o que fazer, alguém tem ideias?
Desde já agradeço.
EDIT4:
Troquei o theme do emerald por outro e já funciona bem :| Devia ser alguma incompatibilidade com o modo de rendering do tema que eu tinha...