Error: Cannot read the portsdb!

[FreeBSD Ports]

System info:
# uname -a
FreeBSD hr-stc-itlab3.virginiadot.org 6.2-STABLE FreeBSD 6.2-STABLE
#0: Tue Sep 25 13:26:00 EDT 2007
toor at hr-stc-itlab3.virginiadot.org:/usr/obj/usr/src/sys/HR-STC-ITLAB3
i386

Message:
I'm trying to upgrade my ports, but I keep getting an error message.
My ports were last updated July 2nd, 2007 and all installed ports were
at their current versions then.  I've updated my ports tree with cvs
and remade INDEX the day before yesterday.  Now I'm following
instructions in UPDATING to upgrade ports that have special
instructions.  This is the error message I get:

# portupgrade -f 'autoconf*'
cd: can't cd to /usr/ports/sysutils/portupgrade
[missing key: categories] [Updating the portsdb <format:bdb_btree> in
/usr/ports ... - 17670 port entries found
.........1000.........2000.........3000.........4000.........5000.........6000.........7000.........8000.........9000.........10000.........11000.........12000.........13000.........14000.........15000.........16000.........17000......
..... done]
missing key: categories: Cannot read the portsdb!
/usr/local/lib/ruby/site_ruby/1.8/portsdb.rb:548:in `open_db':
database file error (PortsDB::DBError)
        from /usr/local/lib/ruby/site_ruby/1.8/portsdb.rb:702:in `port'
        from /usr/local/lib/ruby/site_ruby/1.8/portsdb.rb:890:in
`all_depends_list'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:809:in `tsort_build'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:801:in `each'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:801:in `tsort_build'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:823:in `sort_build'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:827:in `sort_build!'
        from /usr/local/sbin/portupgrade:721:in `main'
        from /usr/local/lib/ruby/1.8/optparse.rb:755:in `initialize'
        from /usr/local/sbin/portupgrade:220:in `new'
        from /usr/local/sbin/portupgrade:220:in `main'
        from /usr/local/sbin/portupgrade:2084

Can anyone help me?

Thanks,
Kevin