well finally i figured it out.... i was having the same problem... i would search for networks, it would say network serch finish and i won't be able to se any networks...
but then i remember when i last flashed my n900 i never updatded the reposotries.... so i went back and added the extradlevel and extra testing and one more... even though i had kernel-power installed on my n900 it was not the new one....

so the moment i aded those repsotires i inidieatly got a ton of updates... when i updated my kernel-power it started working just fine....

pretty stupid but u know i am a human... i forget some times....

so my sugestion would be try updating by adding reposotries in app manager....