Protecting Comps from Sea Air

Well, when not in use, you can cover the computer and/or close the windows to that room and even the door if you like. Yes, that will interfere with the airflow from the windows in the rest of the house but it should help. If you have a flat panel monitor, you can use an old pillow case. For the tower part, you could use an old towel or the like, or just drape a cheap table cloth over the entire desk if that's practical.

This doesn't fix things all the time as you have time during the day when you are using it, but you might as well protect it during down times. I also recommend powering down then, rather than leaving it on 24/7, as that will save you money anyway but it will also be good if the PC tends to overheat. If it overheats and you have cloth over it, you could have a fire, so better safe than sorry and turn it off when it's covered and not in use.