last command - strange entries?

[Saurabh Bhasin]

> The last command uses /var/log/wtmp and /var/log/utmp (mabe even
> /var/log/lastlog) - anyway, the point is, it uses those files to get the
> information, now, it appears as if they have become corrupt, mabe by
> userland/kernel land desynch? bad upgrade? tried a reboot?
> 
> Else, can you give us more details about the system, past upgrades,
> intrusions?

Thanks for the explanation. I do understand the above and for sanity
sake did every single thing to determine if my box was broken into.
However, it turns out that the file did get corrupted (this behavior
started to appear after a system reboot which required manual fsck).

Simple re-creation of the file worked out just fine.