root user error

All of a sudden ,& I am not sure why but 4 some reason I cant use root priveladges anymore.error saying my password is incorrect, but when I type su then passwd in terminal I get this error "%su
Password:
su: setusercontext: Invalid argument"
,Does anyone know what this "setusercontext" error means at all and can I fix it ,as the last time I lost my root privilidges using FreeBSD I had to reinstall, it happened in a similar way " not knowing how it happened" Is there a way I can get root back working?

I really doubt there could be a answer to this so I will have to reinstall 4 the umpteenth time till I get this desktop right ,seems like its a bad idea to touch Kuser when adding to user group etc, it seems to either stop u from logging in at all or takes away root privilidges , FreeBSD really needs to fix this, I tried googling etc & got no where.

Well from GRIEF to half Joy, I fixed getting my Password back it seems using a tutorial from here "http://www.freebsddiary.org/phorum/read.php?f=4&i=189&t=189" But now I cant use my Mouse, I hope to find a solution, if anyone has any tips it would be appreciated