undefined method after freezing rails

Hi,

i've upgraded my rails version to 1.2.1
Cause i've some application build with version 1.1.6, i've frozen their
version
using rake rails:freeze:edge TAG=rev_1.1.6

But now i'm getting an error, if i try to start webbrick.
I've tried to include time class by adding require 'time' to
environment.rb, but this doesn't help.

/usr/local/lib/site_ruby/1.8/rubygems/source_index.rb:92:in
`load_specification': undefined method `parse' for Time:Class
(NoMethodError)
        from
/usr/local/lib/site_ruby/1.8/rubygems/specification.rb:314:in `date='
        from
/usr/local/lib/site_ruby/1.8/rubygems/specification.rb:416:in
`initialize'
        from
/usr/local/lib/site_ruby/1.8/rubygems/specification.rb:412:in
`initialize'
        from (eval):1:in `load_specification'
        from
/usr/local/lib/site_ruby/1.8/rubygems/source_index.rb:128:in `eval'
        from
/usr/local/lib/site_ruby/1.8/rubygems/source_index.rb:92:in
`load_specification'
        from
/usr/local/lib/site_ruby/1.8/rubygems/source_index.rb:128:in
`load_gems_in'
        from
/usr/local/lib/site_ruby/1.8/rubygems/source_index.rb:127:in
`load_gems_in'
         ... 24 levels...
        from
./script/../config/../vendor/rails/railties/lib/commands/servers/webrick.rb:52
        from
./script/../config/../vendor/rails/activesupport/lib/active_support/dependencies.rb:147:in
`require'
        from
./script/../config/../vendor/rails/railties/lib/commands/server.rb:30
        from ./script/server:3

Any ideas how to get rid of this error?

greeting Phil

Are you using the Icalendar gem?

-faisal