First, check your battery connections, at both ends of each cable. Take them off, and clean them if there is any gunk in there. If there is any sign of a problem, get a jump start and see if the problem persists (indicating a weak battery or such). It might be fine though, now that the connections are good.

If there is no sign of corrosion or loose connection, then the battery is the next suspect. Get a jump and take it to an auto parts store that tests batteries (most of the major ones do). Pick one that sells batteries at a good price <img src="/forums/images/graemlins/wink.gif" alt="" />

If that still checks out good...get back to us.