What day was that happening? We've been having some really strong solar storms for about a week. That alone will cause weird things to happen to your GPSr. When I use my Leica survey grade GPS, I check the solar weather websites. If there is alot of solar activity we pack it in. Lightning storms within a 100 miles can cause accuracy problems too. Try this site out: http://www.n3kl.org/sun/status.html or my favorite, http://www.sec.noaa.gov/today.html I guess if it were me I wouldn't be setting out any caches during these periods and finding them could be an exercise in futility. By the way, the manufacturers say that GPS is all weather, and they are as long as they are waterproof. Other than as the previously stated lightning problems overpowering the signal and causing signal degradation, a little rain isn't going to hurt anything. So if you are having problems with lock and location, check out the solar activity, it may be the problem. I check it everyday before I use my survey GPS. Saves me time and fustration.
Mapper Mark