After using the "Star Key" to get into the Alpha Sections H.Q. in "Fountain Square",there are a whole bunch of guards, but only one of them is walking backwards and forwards. How do I get past the guard without setting the alarms off and getting blasted? I have tried everything, I sneak past all the guards that are facing the wrong way, when the walking guard turns around I follow him and sneak up to the next wall, I've even followed him back the other way and then sneak behind him back again (to be sure that I have as much time as possible to get to the next wall without getting blasted),but every time I approach the next wall all the alarms go off and I get blasted. How do I get past these guards?

As soon as he turns around jump up onto the roof, which is to your right I believe... That is, if I have the level you're talking about right.