First off I want to apologize for reviving an old thread but I believe this could be helpful for some people.
I started using MB about a year ago and had the exact same problem since day one. Pasting information didn't work, neither via ctrl-v nor right click --> paste. Every other software worked just fine, so naturally I assumed it had something to do with MB itself.
Today I finally found the solution: My antivirus software (webroot) blocked the pasting! I don't know why it did but after setting the Application Protection setting for MB to 'Allow', it now works fine.
I found the solution at the webroot forums
. I hope this helps some of you people!