FSX black tiles

Hello all FSX people I have an issue when putting more than one of my BGL,s next to each other,these black or missing tiles start to appear they come and go as I move closer and away from the scenery,but never if I only use 1 bgl at a time,the size of the BGL does not matter,but if I use payware photo scenery made up of lots of BGL,s the black areas are further away on the horizon they get filled with texture as I move closer and the area I leave eventually turn black,this only ever happens with photo scenery and not with say UTX,this one has me stuck I have even done a google search,so I am stuck with using one BGL at a time,any ideas are welcome this happens with both SBuilderX and Maps2Bgl_X any help is welcome I cant be the only person this happens to if it is then its time for a new computer