root and user password failed
 

hi all~
i have this weired question. i installed red hat 7.2 and star office yesterday, but today when i try to log in....my password is not working and the kernal command such vi,ls not working too...
but yesterday it was working fine.............i really don't know how to do..........i tried so many times and i'm very sure the password is correct but i still failed............last time when i installed mandrake 8.2 also happened like this once,but i just install again. this time i really don't want to install again without knowing what's wrong..........is this a kind of virus? even my coworkers never see this before and they can't find out what's wrong?
can any one help me?:confused:

the only thing i can think of is fixing it, you may also want to see if you have been hacked - get chkrootkit -> http://www.chkrootkit.org/

to fix passwords look here:
http://cities.lk.net/lost_password.htm