A guess: You are not handling paging in interrupt service rourines correctly.

You will need a 'mirror bit' of p1.0 which you (re)set together with P1.0. You must disable interrupts before manipulating these 2 bits and reenable interrupts afterwards.

Then in every ISR you must save the mirror bit - then set P1.0 to access the memory space you need in the ISR. Then at exit from the ISR restore the mirror bit and set p1.0 to the saved value of the mirror bit. If you have multiple interrupt priorities, you must do even more.

Have fun,

Erik