first of all, seems you are using KM 1.5.x that is outdated now though it remains last official stable version.
But as offen happens in open-source, actual usable version is next beta - 1.6b2. Moreover, the most modern are, so to say, "community remixes" - builds, created by some members as mix of stable, beta versions and new components from Mozilla.
I've just posted list of most usable KM-builds in other thread, so this is simple copypaste:
Try these ones - they don't have any problems with modern-coded sites and are portable so you can use them alongside with your current installation.
Moreover, you can run different KM versions simultaneously if you add parameter
to the shortcuts of every KM:
Give the destop icon of each version it own name. Right click on it and add the parameter "-new" to its start path. if the path has spaces, it must be in "".
Second part is about search in forum.
By default it looks in messages for last 30 days only. And Facebook fix was announced much earlier so you had no chances to find it without changing search options :-)