Socket error from Watir-webdriver with Firefox 6

I am getting this error message while running my watir-webdriver tests on Firefox 6 for the first time on Windows XP.

  1) Error:
testAttributeGadget010_workflow_shown(AttributeGadgetTest):
Errno::EADDRINUSE: Only one usage of each socket address (protocol/network address/port)   is normally permitted. - connect(2)
C:/Ruby187/lib/ruby/1.8/net/http.rb:560:in `initialize'
C:/Ruby187/lib/ruby/1.8/net/http.rb:560:in `open'
C:/Ruby187/lib/ruby/1.8/net/http.rb:560:in `connect'
C:/Ruby187/lib/ruby/1.8/timeout.rb:53:in `timeout'
C:/Ruby187/lib/ruby/1.8/timeout.rb:101:in `timeout'
C:/Ruby187/lib/ruby/1.8/net/http.rb:560:in `connect'
C:/Ruby187/lib/ruby/1.8/net/http.rb:553:in `do_start'
C:/Ruby187/lib/ruby/1.8/net/http.rb:542:in `start'
C:/Ruby187/lib/ruby/1.8/net/http.rb:1035:in `request'
C:/Ruby187/lib/ruby/gems/1.8/gems/selenium-webdriver-2.4.0/lib/selenium/webdriver/remote/http/default.rb:73:in `response_for'
C:/Ruby187/lib/ruby/gems/1.8/gems/selenium-webdriver-2.4.0/lib/selenium/webdriver/remote/http/default.rb:41:in `request'
C:/Ruby187/lib/ruby/gems/1.8/gems/selenium-webdriver-2.4.0/lib/selenium/webdriver/remote/http/common.rb:34:in `call'
C:/Ruby187/lib/ruby/gems/1.8/gems/selenium-webdriver-2.4.0/lib/selenium/webdriver/remote/bridge.rb:410:in `raw_execute'
C:/Ruby187/lib/ruby/gems/1.8/gems/selenium-webdriver-2.4.0/lib/selenium/webdriver/remote/bridge.rb:388:in `execute'
C:/Ruby187/lib/ruby/gems/1.8/gems/selenium-webdriver-2.4.0/lib/selenium/webdriver/remote/bridge.rb:356:in `find_element_by'
C:/Ruby187/lib/ruby/gems/1.8/gems/selenium-webdriver-2.4.0/lib/selenium/webdriver/common/search_context.rb:41:in `find_element'
C:/Ruby187/lib/ruby/gems/1.8/gems/watir-webdriver-0.3.2/lib/watir-webdriver/locators/element_locator.rb:86:in `find_first_by_multiple'
C:/Ruby187/lib/ruby/gems/1.8/gems/watir-webdriver-0.3.2/lib/watir-webdriver/locators/element_locator.rb:33:in `locate'
C:/Ruby187/lib/ruby/gems/1.8/gems/watir-webdriver-0.3.2/lib/watir-webdriver/elements/element.rb:263:in `locate'
C:/Ruby187/lib/ruby/gems/1.8/gems/watir-webdriver-0.3.2/lib/watir-webdriver/elements/element.rb:245:in `assert_exists'
C:/Ruby187/lib/ruby/gems/1.8/gems/watir-webdriver-0.3.2/lib/watir-webdriver/elements/checkbox.rb:19:in `set'
./library/attribOptions.rb:22:in `attribOptions'
./library/attribOptions.rb:20:in `each_index'
./library/attribOptions.rb:20:in `attribOptions'
./007_wb_attribute.rb:365:in `testAttributeGadget010_workflow_shown'
./007_wb_attribute.rb:345:in `each'
./007_w开发者_运维问答b_attribute.rb:345:in `testAttributeGadget010_workflow_shown'

Seems to have happen 20 times out of my 100+ Test/Unit test cases. Has anyone any idea what is going wrong?

Almost sounds like you're running out of ephemeral ports, which shouldn't really happen with just one Firefox instance. But who knows with Windows. Try increasing the MaxUserPort setting as described here.