What is process dirt.exe?

My first post, so apologize in advance if not following correct protocols.  Running Windows 7 on an HP p6774y desktop.  Primarily use Firefox for a browser.  At startup tonight, lots of hard drive access, which seems to happen from time to time.  Opened Task Manager just in time to see a process dirt.exe, with very high PID count, bounce around the top couple of processes then disappear.  Quick Google search was not encouraging so thought I would inquire on the Norton forum for any insight.  Any help appreciated!