Debian – Do some debian builds not have lsb_release

Every time kernel starts it tries to use swap partition to load its saved state (from suspend to disk). If there was no state saved, then it will produce such error. It's normal and harmless.

I'd suggesting to make your monitoring script to ignore this specific message (don't know if you're using a custom solution or a ready product, but you'll have much more messages to add to ignore list, so this will be a good exercise either way).

Your sources.list entries are for stable, which is "squeeze"/6; if you were really using those on a Debian 4 system, you probably have a very confused system now. An apt-get dist-upgrade might be able to bring things into sync (by bringing you up to stable, i.e. Debian 6); you probably can't get your old system back if packages have been overwritten by the "squeeze" packages.