new dhcp scope

I'm change subnets on a network of win 98 machines. The
98 machines will not accept the new scope with the new
subnet. I'm changing from 10.251.86.xxx to 10.251.85.xxx.
I ran into this problem about 2 years ago. I was able to
find a tech doc that had a batch file of some kind that
fixed this problem.

Thanks,
Chris