Studio XPS 1340 wireless problems

My XPS 1340 has an intermittent problem obtaining full network connectivity from wireless access points and occasionally the wireless card and bluetooth refuse to respond at all, forcing a hard reset with the power lead unplugged.details pasted in below.

the problem seems to be worse since i switched to a wireless-n router (from wireless-g) in my home office.

since i made the post below i have noticed that a major controbutor to the problem seems to be unplugging the power supply (or plugging it in) while the machine is in standby/sleep mode. that often seems to trigger the problem as below when i next wake it.  as the machine is designed to be portable, this is a concern.

The XPS 1340 has a Dell 1515 wifi card with driver 7.6.0.168, a dell 370 bluetooth mini card driver 6.1.6002.18005 runs Vista ultimate 32 bit (not the 64 bit which Dell tries to push as standard) and has BIOS A11 which has improved overall stability.  I now have a D-Link DSL 2740-R router with the latest firmware which works well.

The wireless problem may be related to the wider instabiltiy problems the XPS 1340 is having, but the thread below discussing the problems mainly focusses on the BSOD

http://en.community.dell.com/forums/p/19268687/19590069.aspx#19590069

so i have created a new thread here to focus on the networking issue

reproduced here is my post on the problem in the forum discussing the BSOD issue

>>the wireless problems have come back six weeks after updating to BIOS A11 .

All was fine/perfect for four weeks but in the last two weeks, intermittently on sleep/wake the wireless symbol flickers on and off and the XPS 1340 often, but not always cannot make a proper connection to wireless networks.  it connects to the wireless network (slowly 'taking longer than normal') but cannot break out to the internet - reporting a local connection only.  on the same wireless network (my main network is a Linksys WAGN with latest firmware) other computers - apples, netbooks running XP and vista machines all work fine getting out the the internet with no problem.  when i plug the XPS 1340 into sae router using a CAT5 cable it works fine.  the problem occurs on a wide range of public and private networks i use as i travel around and isn't just limited to my main home network.

the wireless button often, but not always works turning the card on and off.  but the XPS 1340 still refuses to make a conenction to the internet making only a local connection.  often the XPS 1340 does not conect at all.  while this problem is occuring the number of wireless networks the XPS 1340 can detect also seems to drop, presenting only a short list.

I try a range of windows diagnostics (resetting IP addresses, restarting the wireless card etc in case there is aproblem at the router end) but these don't work.  the only solution is a hard reset and then the XPS 1340 resumes working normally for a few sleep wake cycles until the wireless problem returns.  I have all the latest drivers.

this problem is quite maddening for a £1,100 laptop and still seems to be a BIOS problem around the soft multimedia buttons and the wireless card.  BIOS A11 seems to be a temporary fix only.