Because Joomla! 1.0.13 is a security release, it is important that you upgrade but we strongly recommend that you take extra precautions when performing this upgrade. This release features several improvements to the password storage system designed to help protect the future security of your Joomla! powered website. These changes will cause compatibility issues with some 3rd Party Extensions, especially bridges. If your Joomla! site utilizes bridges to other applications or extensions that have their own login system such as Community Builder, Virtuemart, or others you should not upgrade your site until those extensions have also been updated.