Undefined method `each' for (installing gem)

I frequently get this error. Halp?

C:\Documents and Settings\Owner\My Documents\My Dropbox\Code>gem install
sinatra

Successfully installed sinatra-1.0
1 gem installed
Installing ri documentation for sinatra-1.0…
Updating ri class cache with 2857 classes…
Installing RDoc documentation for sinatra-1.0…
ERROR: While generating documentation for sinatra-1.0
… MESSAGE: Error while evaluating
C:/Ruby191/lib/ruby/gems/1.9.1/gems/rdoc-2
.3.0/lib/rdoc/generator/template/darkfish/classpage.rhtml: undefined
method `eac
h’ for #String:0x30cd9e0 (at “r”>Namespace\n\t\t\t\t<ul
class=“link-lis
t”>\n\t\t\t\t\t")
… RDOC args: lib README.rdoc LICENSE
(continuing with the rest of the installation)

On Wed, Jul 28, 2010 at 10:01 PM, Sonja Elen K. [email protected] wrote:

Updating ri class cache with 2857 classes…
(continuing with the rest of the installation)
Try updating rdoc.