You probably aren't terminating your code, so the system goes on, and on, and in some cases, once it reads the last byte of internal memory, it goes to external memory, overriding ports P0 and P2, because P0 and P2 are not available when I/O to external or code memory is done.

As for the RD and WR lines (Port P3.6 and port P3.7), make the value high if you want to enable them as inputs, or better yet, don't adjust the values for Port 3 at all.

To terminate your code, make an instruction that causes the system to jump to the same instruction over and over again.

In some assemblers, this is acceptable:

jmp $

also, you could try:

ajmp $
sjmp $
ljmp $

or if the $ is not supported, you could try:

code:
ajmp code

What assembler are you using?