In Poe's "The Raven," what is the narrator doing at the beginning of the poem? What actions disturb him in the first stanza?

At the beginning of this poem, the narrator is sort of dozing, or "nearly napping," he says, in his room—perhaps a library or study of some kind (as it contains books and a bust of Athena)—and "ponder[ing]" an old book full of "forgotten lore." He is also hoping that his books might distract him from the terrible grief that he's feeling. He says, "vainly I had sought to borrow / From my books surcease of sorrow," sorrow over his dead lover whose name, he tells us, was Lenore.  
In the first stanza, the action that disturbs him is a "rapping at [his] chamber door." He hears a soft tapping at an outer door of his room, a door that leads outside. He assumes it is "'some visitor,'" and he tries to reassure himself at the end of the stanza that this is the source of the odd rapping. It does seem a bit strange that a visitor would be stopping by at this time, however. The narrator has already told us it is a dreary "midnight," and we soon learn that it is also December: hardly a hospitable night and time to be out and about in the cold and darkness.

At the beginning of the poem, the narrator is poring over "many a quaint and curious volume of forgotten lore." The mood of the poem is "dreary" from the very first stanza; we are told that it's midnight, and the narrator is feeling "weak and weary." There's a dark, gnawing discomfort in the atmosphere. In the midst of this melancholic state of mind, the narrator is poring over volumes of old, forgotten stories. He's restless, alternating between nodding off to sleep and reading the strange volume of old stories.
We get the impression that the narrator's mind isn't really on what he's reading; he struggles to stay awake but is soon interrupted by a knock on the door. He tells himself that "Tis some visitor...Only this and nothing more." It's as if he's trying to convince himself about something. The second stanza sheds a little more light on the true reason for the narrator's despondency. He's reading to try to distract himself from the grief of losing a "rare and radiant maiden" named Lenore. From his books, he hopes to find a "surcease of sorrow," but his efforts are in vain. Perhaps the gentle knocking on the door causes him to hope that it's Lenore, and he has to tell himself otherwise in order to quell the likely disappointment that reality will bring him.