The sudo timestamp problem happened to me on a freshly installed Edgy (xubuntu), without my ever actively resetting the clock at any time. Like kko, I had a lockup (bug 41340), pulled the power plug, then rebooted, which may be what somehow caused the timestamp difference.
The system clock (as shown by /bin/date) was within a minute or two of the correct time. I don't know what file's timestamp sudo was checking, so I can't say whether it was in the future or past. Curiously, the workaround (found by googling: lots of people are hitting this on Ubuntu) was to set the date to the future deliberately (using the gui time/date tool, which apparently doesn't need sudo) then run sudo -k -- even though it seems like that's exactly what this bug report says doesn't work. -- "sudo -k" fails when timestamp is in the future https://launchpad.net/bugs/43233 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs