Boot up problem with Kernel 2.4.8

[Bao C. Ha]

I have a strange problem with kernel 2.4.8.  When
I tried to boot up with "root=/dev/mtdblock/3", it
gets panic and can't find the root device.  When,
I change to "root=1f03", it works.  I am using
RedBoot if it matters, but it works with 2.4.5
before.

Appreciate any comments/suggestions.

Thanks.
Bao