Posting in the Magento forums has been disabled pending the implementation of a new and improved forum solution which should better serve the community.
For new questions please post at magento.stackexchange.com, the community-run support site for the Magento community. We will be providing updates on the new forum solution soon. For questions or concerns please email email@example.com.
“Fatal error: class ‘Helper_Data’ not found in domainfolder/app/mage.php on line 546”
I think there is some mistake into the module you have used. So first of all, remove that module completely from Magento, try to run you Magento without disturbing the core part. The error may be depended on some core files that have been overwritten into that module.