I've experienced this a few times, note the AP was up and running:

Jan 13 10:55:26 marsupilami kernel: [    7.149411] iwl3945: Error sending REPLY_RXON: time out after 500ms.
Jan 13 10:55:26 marsupilami kernel: [    7.149419] iwl3945: Error clearing ASSOC_MSK on current configuration (-110).
Jan 13 10:55:27 marsupilami kernel: [    7.705032] iwl3945: Error sending REPLY_RXON: time out after 500ms.
Jan 13 10:55:27 marsupilami kernel: [    7.705039] iwl3945: Error clearing ASSOC_MSK on current configuration (-110).
Jan 13 10:55:33 marsupilami kernel: [   13.461886] wlan0: No ProbeResp from current AP 00:14:bf:64:95:24 - assume out of range
Jan 13 10:55:33 marsupilami kernel: [   13.462868] wlan0: RX deauthentication from 00:14:bf:64:95:24 (reason=7)
Jan 13 10:55:33 marsupilami kernel: [   13.462875] wlan0: deauthenticated
Jan 13 10:55:34 marsupilami kernel: [   14.463446] wlan0: authenticate with AP 00:14:bf:64:95:24
Jan 13 10:55:34 marsupilami kernel: [   14.464639] wlan0: RX authentication from 00:14:bf:64:95:24 (alg=0 transaction=2 status=0)
Jan 13 10:55:34 marsupilami kernel: [   14.464644] wlan0: authenticated
Jan 13 10:55:34 marsupilami kernel: [   14.464647] wlan0: associate with AP 00:14:bf:64:95:24
Jan 13 10:55:34 marsupilami kernel: [   14.466118] wlan0: authentication frame received from 00:14:bf:64:95:24, but not in authenticate state - 
ignored
Jan 13 10:55:34 marsupilami kernel: [   14.467703] wlan0: authentication frame received from 00:14:bf:64:95:24, but not in authenticate state - 
ignored
Jan 13 10:55:34 marsupilami kernel: [   14.469111] wlan0: RX ReassocResp from 00:14:bf:64:95:24 (capab=0x411 status=0 aid=1)
Jan 13 10:55:34 marsupilami kernel: [   14.469115] wlan0: associated
Jan 13 10:55:39 marsupilami kernel: [   20.141377] wlan0: No ProbeResp from current AP 00:14:bf:64:95:24 - assume out of range
Jan 13 10:55:39 marsupilami kernel: [   20.142350] wlan0: RX deauthentication from 00:14:bf:64:95:24 (reason=7)
Jan 13 10:55:39 marsupilami kernel: [   20.142357] wlan0: deauthenticated
Jan 13 10:55:39 marsupilami kernel: [   20.143477] wlan0: RX deauthentication from 00:14:bf:64:95:24 (reason=7)
Jan 13 10:55:39 marsupilami kernel: [   20.144446] wlan0: RX deauthentication from 00:14:bf:64:95:24 (reason=7)
Jan 13 10:55:39 marsupilami kernel: [   20.145230] wlan0: RX deauthentication from 00:14:bf:64:95:24 (reason=7)
Jan 13 10:55:39 marsupilami kernel: [   20.146276] wlan0: RX deauthentication from 00:14:bf:64:95:24 (reason=7)
Jan 13 10:55:39 marsupilami kernel: [   20.147286] wlan0: RX deauthentication from 00:14:bf:64:95:24 (reason=7)
Jan 13 10:55:39 marsupilami kernel: [   20.148289] wlan0: RX deauthentication from 00:14:bf:64:95:24 (reason=7)
Jan 13 10:55:40 marsupilami kernel: [   21.147900] wlan0: authenticate with AP 00:14:bf:64:95:24
Jan 13 10:55:40 marsupilami kernel: [   21.149108] wlan0: RX authentication from 00:14:bf:64:95:24 (alg=0 transaction=2 status=0)
Jan 13 10:55:40 marsupilami kernel: [   21.149116] wlan0: authenticated
Jan 13 10:55:40 marsupilami kernel: [   21.149120] wlan0: associate with AP 00:14:bf:64:95:24
Jan 13 10:55:40 marsupilami kernel: [   21.150652] wlan0: authentication frame received from 00:14:bf:64:95:24, but not in authenticate state - 
ignored
Jan 13 10:55:40 marsupilami kernel: [   21.153184] wlan0: RX ReassocResp from 00:14:bf:64:95:24 (capab=0x411 status=0 aid=1)
Jan 13 10:55:40 marsupilami kernel: [   21.153191] wlan0: associated
Jan 13 10:55:46 marsupilami kernel: [   26.812868] wlan0: No ProbeResp from current AP 00:14:bf:64:95:24 - assume out of range
Jan 13 10:55:46 marsupilami kernel: [   26.813849] wlan0: RX deauthentication from 00:14:bf:64:95:24 (reason=7)
Jan 13 10:55:46 marsupilami kernel: [   26.813856] wlan0: deauthenticated
...