Hi Swapna,
I also faced this problem. There is nothing to do with data size of SNA nodes and links tables. Even if you zoom the network diagram (with 3 nodes and 3 links), it will change its direction.
After I zoom, I used to press "-" and "+" to go to specific nodes. It is very tedious task to do it. But I don't have any other option.
Swapna, Have to ever used proc optgraph or Network statistical measures like communities and so on.
Please let me know your inputs.
Thanks,
Urvish