read-only file system

["T.V.Gnanasekaran" <gnana@lanminds.com>]

Hi,
I upgraded to potato from slink 4-5 days ago.
I can't create dir in /usr/doc area. I get:

genome:/usr/doc# mkdir test
mkdir: cannot make directory `test': Read-only file system
genome:/usr/doc# 

any idea why this behavior?
-gnana