I just installed the latest Windows version from Activestate (having
completely removed earlier version) ruby186-25.exe and that is working
fine:
    C:\ruby\bin>ruby -v
    ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]

however when I came to work through tutorials I found Ri wasn't
working quite as I expected:

C:\ruby\bin>ri String#tr
--------------------------------------------------------------
String#tr
     tr(from, to)
-------------------------------------------------------------
     (no description...)

according to the tutorial I should get a lot more info about
parameters, example of usage etc. from last time I played with this I
thought it was more informative, have I missed an important step in
the installation?