This has happened more than once to me now; every time in Crux, but never in Arch (or Ubuntu). When I’m compiling a package — usually one of the core packages like make or gcc or something — I get clock skew warnings, along with a message that the file modification times are thousands of seconds into the future.
The funny thing is that it seems to trigger some kind of pause in the compilation process. On both my Thinkpad and my Pavilion now, compiling software that suffers from that particular warning takes longer than it should (particularly on the faster machine).
Digging around on the Internet suggested that it meant I had downloaded a package that was time-stamped from a zone further east — and was particularly fresh. In other words, it isn’t yet then here now. It’s still now here and not then, like it was there. Does that make sense? 
A little logic and a bit of experimentation yielded a very easy, very quick solution: From another terminal, I entered a date -s command that pushed the system clock a day into the future. When I bounced back to the compiling terminal, it was like someone had pressed a button. It immediately started speeding up again, with no more warnings.
I let the package finish compiling then jumped back to the other terminal and corrected the date. And so life goes on. … 
what command do you use to set the system date back to the correct time
I just eyeballed it and set it to a day in the future, then the local time within a minute. Both of them looked like this:
date -s "2008-03-13 20:26:00"Or as close as I liked to the actual time. As you might suppose, I needed to be root to do that (or sudo, anyway).