I had similar issues, my victim machine was Wireless and the machine was 3 feet away from me, i could set up the routing tables fine, and the arp spoof, but ocasionaly the victim machine would loose all network access including internet "Limited or No Connectivity" and when it did stay connected i failed to ssl strip, the back track box will post http traffic and everything, all the headers, as soon as i went on an HTTPS Site, it would go through flawless and the back track box wouldn't batter an eye lid, wouldn't even try to grab the https traffic or passwords.

Im using the WNR2000 Netgear router. Windows 7 with DLINK Wireless dongle via the N Band wireless protocol.