Rail breaks when using large map

When on a rail line, opening up a 2x zoom map caused all rail and red-stone related items within a given area to break. I had just updated to the newest version and had just tried out a new map. the rail was affected to a point. a portion close by did not break( the powered rail was off), but the powered section and regular rails connected to them were broken to about a 30 block radius at the point where the rail started going uphill. After fixing the rail, I went upstairs to find a section above me had also broken, and had already disappeared. It happened once more a little later, but since I have not been able to repeat it.

What I expected to happen was...:
I was just using a rail line built in my mine a long time ago to go from different points underground to above ground. I decided to open up my map to check out the new zoom and start filling it in.

What actually happened was...:
As soon as i set off, a large portion of rail and red-stone related items;ie a lever, button, red-stone torch all broke and I had to scramble to pick it all up. This only affected certain portions of the rail, to which I cannot seem to connect