Not able to put licence for Resharper 6.1

I have a licence valid for 6.1 resharper. I was using 30 day free trial of Resharper 7.0, that has expired. Now there is no place where I will be able to put the licence key. I have uninstalled all the previous versions of Resharper and I have installed 6.1 but the resharper tab is not coming on menu bar. If I navigate to tools >> options >> Resharper it displays an error message "An Error occured loading this property page".