I have the same problem with a brand new m6400. The wlan utility can see the networks in its site survey but doesn't list them in avaliable networks. I can connect on reboot but there is no way to connect without rebooting once you move to a different ap. The laptop cannot go to sleep or it needs a reboot. Let this utility manage my wireless networks is greyed out so I cannot try windows' utility.

You wouldn't happen to be running nod32? I am wondering if that is my problem as it did allow me to choose a network first time out the box but now I can never get one listed even though I can cause the connection to work through DCP after a reboot.

I got mine working with windows' utility by doing:

Open the "Dell Control Point" software.

Select  "Connection Manager".

Click on the "Connections" button.

Select  "Profiles".

Select  "Change Settings".

Select "Program Settings".

deselected the Wi-Fi check box.

Using the windows utility works ok for me now.

I have a work laptop Dell Latitude E6500 and had nothing but problems with the Dell ControlPoint software & services.  I would come into work to a BSOD (Blue Screen of Death) at least 3 times a week.  I disabled ALL Dell ControlPoint services and startup items and now no more issues.  Event log was red all over the place due to issues with this junk.  After disabling services and startup items for the ControlPoint software no more BSOD in the middle of the night and all blue event log entries.  Have seen no negative impact on machine's performance or stability.  In fact, and as a good techie knows, disabling the services and startup items has actually made the system more responsive. 

Start > Control Panel > Add remove programs > Select all Dell control point installations one at a time > remove > wait > go on to the next badly written Dell program and repeat until all are removed > reboot as needed.

Start > control panel > Administrative Tools > Services > verify Wireless Zero Configuration service is running.  If not Windows wireless is none responsive - From this same window > select Wireless Zero Configuration > near top left of window click "restart the service".  Use Windows wizard to manage all wireless connections.

These Dell applications are intermittent at best, and knowing Microsoft, they will build a service pack or patch to conflict with them sooner or later.  If that is not the cause of this software failure now.

Steve

I "did" use Dell CPM--I also had all the above problems.  It was determined by the TSD that the Dell Control Point Manager was the source fo most all of my problems.  Once it was fully gone from my system, only then did it start performing like a great machine that it was.  CPM is the root of all evil!  :-/  

PROBLEM: there isn't a QualComm dialer for the internal Dell Broadband card.  I have determined that it is far better NOT to use that feature in lieu of the Control Point-less app.