sounds like you need to just down load the blank stage template and start over. the move function seems to work better when you just want to move a short distance. i use cut and paste for big moves. the move function seems to want to jump to an "edge" of another object or a section on the "grid". when selecting multiple objects, make sure you don't select the grid or berms this will mess you up for sure. sounds like every thing has been "selected". find a spot and select it, hopefully this will unselect every thing else.
the group and explode is use to modify a component. if you are modifing a component, be sure to make if "unique", or the multiple same components will be modified as well.
good luck.
lynn
p.s. i finished sketchuping the area 2 stages and have posted them to the 3d warehouse, just search for "godsmack".