Shouldn't have any thing to do with the hard wired switch, but are you
located near a military base. The military recently took back and started
using frequencies that garage door openers use. Sears recently posted a
notice that some older openers would start having difficulties because of
this. I seem to remember that they came up with a retrofit of some kind
that would alleviate the problem. And of course, all new openers now use a
different frequency.
Tom.

Ditto........find a way to eliminate the remote signal input. Remove
and/or short the antenna if appropriate. Use the wired switch until
you can reasonably say that a unwanted remote signal is the problem