when creating a new controller the file name of the controller has to be the same as the controller itself and it can be either xxxxx_controller or just xxxxxx
mytest_controller.rb - ok
mytest.rb - ok
mytest_co.rb - not ok
also make sure you add ::BASE after the class name definition or you will get a horrifying error... well not horrifying but at least not the result you are expecting.
As always, this applies to WINXP - LAMP - ROR installation