Perhaps I posted this before, but if not, I am posting again for my reference.
Use this tool to view SharePoint 2010 Error Logs:
SharePoint 2010 Log files are usually located here, sort by date and open the latest one in the ULS Viewer:
C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\LOGS
Create a “Filter” and select “Message” and enter “Error” in value. This should give you all error entries in the file and you can find out what is wrong.