Christophe, can you please try 0.12 qemu-kvm packages from my site, http://www.corpit.ru/debian/tls/kvm/ and see if these fixes your problem?
This bug is difficult to reproduce, upstream says it's fixed long ago, and it also seems to affect only Intel machines, but I only have AMD CPUs here. The packages I mentioned are not in Debian because they're not yet DFSG-clean, because since 0.12 the way various bios/firmware bits are packages has changed in upstream and we were waiting for new seabios package to enter Debian (it's now separate "subpackage"). Packages on my site includes the already compiled binary form of seabios, but other than that they're as good as possible. Thanks. /mjt -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org