Issue : click_no_wait is not working for CHECKBOX
Purpose : To Handle the pop up (It occurs after clearing the checkbox.)
Solution: Make sure the installed ruby version is 1.8.6_26 .
If oyu already installed Ruby 1.8.6_27 then please reinstall the ruby software.
Thanks to Arman and Watir.com to suggest this solution
NOTE: Watir.com suggests to use Ruby 1.8.6_26.
Raveendran 