This is a register issure
I know for the free this will work
HKEY_CURRENT_USER\Software\Google\SketchUp8
save the old sketchup 8 register key and make 2 copy
delete old sketchup 8 reg register
now
reinstall new sketchup 8 to differnt location
move a copy of plugins to new sketchup 8
now it should work for the new and old
edit old reg to tranfer back setup infor you want to bring forward to new register.
once in a wild copy plug-ins back to old to keep toolbars link