error to run reporting service

When I try to run the web page which host the report, I am not able to reach the home page and following error show up.

" The report server cannot decrypt the symmetric key used to access sensitive or encrypted data in a report server database. You must either restore a backup key or delete all encrypted content and then restart the service. Check the documentation for more information. (rsReportServerDisabled) Get Online Help
Bad Data."

I then went to Reporting Services Configuration Manager -> Encryption Keys

then I clicked the Change button

after all these I can get back to the reporting service home page. Any one can tell me the reason of this error? thanks

when I tried to open the reporting service web site. The following error pop up

The report server cannot decrypt the symmetric key used to access sensitive or encrypted data in a report server database. You must either restore a backup key or delete all encrypted content and then restart the service. Check the documentation for more information. (rsReportServerDisabled) Get Online Help
Bad Data.

Then I go to Reporting Service Manager-> Encryption keys. After I changed the encryption keys; the reporting service works again. Could anyone explain the reason behind this? ans is that the right way to reslove the error?

Thanks

|||Reporting Services data is encrypted. Did you restore the database or change the service account not through the Condifguration manager ? After changing / deleting the key 8and the encrypted content) the database was empty, you had a new key and you could start all over.

Jens K. Suessmeyer.

http://www.sqlserver2005.de