I encountered a weird login problem recently. I gather from looking
at dejanews that others have had similar problems.
My system (Slackware with 2.0.34 kernel) suddenly and for no
apparent reason stopped letting me log in (as root or anyone else).
After trying a few other things, I surmised it might have something
to do with shadow passwords. I booted using my boot and root
disks, then mounted my hard drive (mkdir tmp; mount /dev/hdb1 tmp).
Then I removed (actually, renamed) the /etc/shadow file on the hard
drive and removed the passwords from a couple of accounts in
/etc/passwd on the hard drive using sed (cp passwd passwd.orig;
sed s/root:x/root:/ passwd.orig > passwd). Then I could log in
again (what a relief!). I still don't really know what caused
the problem, though.
Now I can only run Xwindow as root--it gives me an error message
"xf86OpenCOnsole: Server must be suid root" otherwise--why should
an application like Xwindow know or care about shadow passwords?
Anyway, that's tomorrow's problem.