This

then did a apt-get update, apt-get install firmaware-linux (else I loose the network/sound/video drivers) and finally apt-get upgrade.


has the capability of breaking your system in wonderful ways.

If you have updated your sources the correct sequence of events is:

apt-get update && apt-get dist-upgrade && apt-get install firmaware-linux

Package dependencies change between releases so upgrade is not the right command.
You can use upgrade intra-release.