Database Problem

Hi I am facing a problem while loading my database. Whenever i opened a database i get a message that Other concurrent activities have reused the available space in the database that contains ur snapshot data. And because of this problem i m not been able to do my daily transactions in the system. Can anybody put some light on this to how to solve this problem. You can reply me back at sjagjeet@hotmail.com Regards Jag Singh Jagjeet