If we were to count the number of annoying errors one encounters in Magento; we’d need an entire century. 1 of them comes after you upgrade Magento CE to 1.4.x. This happens when you try to access the Magento Connector. You get a 404 Error page no matter how you try to access the Connector.
Solution:
The fastest and easiest solution is to run Magentos clean-up. All it essentially does is to reset the file permissions and clear out all Magentos’ miscellaneous cache folders.
Get it here : http://www.magentocommerce.com/wiki/groups/227/resetting_file_permissions
The longer route is to do what the cleanup does; manually, and I know you are not going to try that.
