Error while vacuuming table

Hello,

When I run vacuum, I get:

vacuumdb: vacuuming of database "pm50" failed: ERROR:  catalog is
missing 1 attribute(s) for relid 4210163

How do I go about debugging this? I have googled around and tried a few
things to no avail.

Any pointers will be appreciated.

Thanks.
Nikhil