Have the same problem on my new Dell Inspiron 17R, it drives me nuts!
Connection drops for a few seconds every several minutes or so. When I ping my router I often see timeouts.
I am using the latest driver v15.8.0.5, AES WEP-2, router is Linksys X3000.
I tried turning wireless power management off, tried different channels, tried lots of other settings - nothing helps.
When I disable 802.11n, connection becomes more stable, but still drops from time to time.
Here is how it looks in the Wireless Event Viewer:
1,S24EvMon,07/20/2013 12:06:44,Success,Driver,SYSTEM,RxAssocResp (my MAC here) 6 -45
2,S24EvMon,07/20/2013 12:06:44,Success,Driver,SYSTEM,RxAuthSuccess (my MAC here) 6
3,ZCfgSvc,07/20/2013 12:06:44,Information,Security,SYSTEM,Authenticating Wireless Profile: dop 2
4,S24EvMon,07/20/2013 12:06:44,Information,Driver,SYSTEM,ATC (my MAC here) dop 6 RSSI=-42
5,S24EvMon,07/20/2013 12:06:44,Information,Driver,SYSTEM,AddToExclude (my MAC here) dop 6 WEV_EXCLUDE_LIST_REASON_802_11_AUTH_FAILURE