ntdll.dll internet explorer crashing help

i use mozilla normally but have internet explorer installed on the computer. but even though im not using internet explorer, it keeps appearing then disappearing at regular intervals on the windows task manager under the processes tab. it will also routinely say that there is an error and it needs to close; the error always associated with the file ntdll.dll.
this is disturbing the function of other programs.
could it be a virus?
how can i get rid of the problem (which just started out of the blue)