Rails 3.1 string conversion errors

I’m seeing many errors when installing Rails 3.1 and other gems.
These are all showing up in the ri/rdoc portion of the install
sequence and look like this:


gem install rdoc
Depending on your version of ruby, you may need to install ruby rdoc/
ri data:

<= 1.8.6 : unsupported
= 1.8.7 : gem install rdoc-data; rdoc-data --install
= 1.9.1 : gem install rdoc-data; rdoc-data --install

= 1.9.2 : nothing to do! Yay!
Successfully installed rdoc-3.9.4
1 gem installed
Installing ri documentation for rdoc-3.9.4…
unable to convert U+201D from UTF-8 to US-ASCII for lib/rdoc/text.rb,
skipping
unable to convert “\xC3” to UTF-8 in conversion from ASCII-8BIT to
UTF-8 to US-ASCII for History.txt, skipping
Installing RDoc documentation for rdoc-3.9.4…
unable to convert U+201D from UTF-8 to US-ASCII for lib/rdoc/text.rb,
skipping
unable to convert “\xC3” to UTF-8 in conversion from ASCII-8BIT to
UTF-8 to US-ASCII for History.txt, skipping


ruby --version
ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-darwin10.8.0]

Any idea what’s going on?

thanks in advance
Rick