I might have been too quick with the previous - everything seems to be
working on the ThinkPad under 8.99.7 right now. It is indeed with the
8GB memory and immediately after the reboot, so memory fragmentation
is unlikely, but nevertheless it works with all the sticks and
external disks which failed earlier. Also, when I did the tests
earlier, I was in the middle of an incremental build plus a few
packages on the side, so memory fragmentation was possible (yet,
collectd was showing some 30-40% memory free in that period).