rails rake (3.1) why do all rake tasks error out with 'stack level too deep'

Possible conflict with Rake extension maybe?

md:~/Dropbox_not_syncd/webs/3/tdd/rubyists$ rake db:drop
/home/durrantm/.rvm/gems/ruby-1.9.2-p180/g开发者_如何学Goems/rake-0.9.2/lib/rake/version.rb:4: warning: already initialized constant MAJOR
...
WARNING: Possible conflict with Rake extension: String#ext already exists
WARNING: Possible conflict with Rake extension: String#pathmap already exists
/home/durrantm/.rvm/gems/ruby-1.9.2-p180/gems/rake-0.9.2/lib/rake/task_arguments.rb:73: warning: already initialized constant EMPTY_TASK_ARGS
..
rake aborted!
stack level too deep

(See full trace by running task with --trace)

An answer to my problems - at least they have gone away and I can move on - was to use
bundle exec rake spec
over
rake spec

Some time later....

eventually I was able to blow away my rcm or at least delete all rvm related files and then I could go back to use 'rake spec', etc. Though I did also create and repopulate the application too along with this.