Garmin 305 problems

I've been really disappointed with the Garmin 305. The first one misted up then died completely when I used it in the rain (it's supposed to be submersible in water). Got a replecement which locked up completely the first time I tried to download a Tracklogs route. I'm now on my third and the cadence monitor has died after just a week This is not a sensor positioning problem as I have tried it virtually touching the unit. Anyone had similar experiences?