If something does not work as expected, before starting further Magento troubleshooting of the issue please try the following steps:
- reindex all indexes at System > Index Management
- make sure the compiler is disabled
- flush Magento cache at System > Cache Management
- logout from Magento backend interface
- clear your browser cache and cookies
- login to Magento backend interface and check if the issue is solved
The steps above should solve the most common issues and save you some time before starting detailed throubleshooting.