SystemTimer not installing correctly

Here is the output when I try to install the gem:

Building native extensions. This could take a while...
Successfully installed SystemTimer-1.2
1 gem installed
Installing ri documentation for SystemTimer-1.2...
Updating ri class cache with 6252 classes...
/Users/chabgood/.gem/ruby/1.8/gems/rdoc-2.4.3/lib/rdoc/ri/driver.rb:
818: [BUG] Bus Error
ruby 1.8.7 (2010-01-10 patchlevel 249) [i686-darwin9]

Any idea why this is happening, on a mac?

When I rake unpack the gem there is nothing in the directory.