Perhaps some sort of script is interfering with it. Type /remote off
and then wait for people to talk (if you can't be bothered to wait, just join some huge channel and check out the join/parts).
Secondly, try disabling and re-enabling timestamp. Just use /timestamp off
and then /timestamp on
Finally try running a Search
on "timestamp" and see if this has been covered before. Expand to 'All Forums' and expand the date range to 'All Posts' for best results.