I now can definitely confirm that it is virtualbox 4.1.18-dfsg-2+deb7u1 which causes the hangs.
During an uptime of 1 week I performed 22x s2ram including 7x over night *without any VM up and running*. I did not notice any problems or glitches. The VM is running OS/2 as a guest with 1 CPU and 96MB of RAM assigned. Networking is in bridged mode, so NIC is in promiscous mode when VM is running. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org