Strange shutdowns

[rhdeurope]

Hi everyone

Any ideas why my macbook pro 13" shuts down if I move it when it is plugged in on mains power? When it's on battery alone it's absolutely okay. I've had the computer for 2 yrs and this only started happening a few months ago. If it's plugged in and, for example, on my lap and I move it to the table, if I hear the click of the sudden motion sensor engaging, everything goes black. So I restart it, it takes a while to boot up, then says "Your computer's clock is set to a date before Jan 1, 2008. This may cause some applications to behave erratically." So I set the time/date manually, but it takes 10 mins+ before it will find wifi, saying "none of your preferred networks are available." Then when I plug the magnet mains cord back in, the green light doesn't go on, so I unplug it from the wall, wait a few seconds, plug it back in and then it's okay. Many thanks if anyone has a suggestion.
Mac OSX 10.6.8
Battery Health Information:Cycle count: 93 Condition: Normal