Recently my iRiver  H320 had some milk based drink spilt on it. I’m not sure what the drink was (I discovered it when my iRiver stopped working and the drink was dry) but it smelled like coffee or hot chocolate when I washed it off (I considered tasting it but decided that knowing exactly which drink had damaged my iRiver probably wouldn’t help me fix it).
The initial problem was that no buttons other than the play button (which is also used to turn it on) worked. When I first discovered this I had no way of hitting the reset button so my iRiver played until the battery ran flat. I tried to disassemble it by removing the five tiny phillips-head screws from the sides, but that didn’t make any part of it loose. I tried using a small amount of force on the front piece of plastic and broke two of the clips that hold it in place while getting another two loose without breaking (but there were still at least four clips to go).
Then I realised that the problem was that the keys were physically sticking and that maybe if I washed the keypad out I might get it to work. So I spent some time in a cycle of dripping water into my iRiver, pressing the buttons to get some of the nasty stuff dissolved, and then using a towel to soak up some of the water with milk or whatever. After repeating this for a while the buttons all seemed to work well apart from the play button which kept registering presses when I wasn’t touching it. This meant that it always automatically turned on and then played a song in a stuttering manner as the play button is also the pause button and it paused and played as rapidly as it could.
Finally I left it in the sun to dry for a few hours, which seemed to do some good. The play button mostly works now. Also it seems quite easy to get water between the front layer of protective plastic and the layer behind (which actually houses the keypad). So I have several large drops of water spread out between the layers which move around as I squeeze it. I think that if I get that dried out before algae can grow then everything will be fine.