Win 7 (Pro) will not connect to wireless Networks

[SanDiego7697]

I'll 1st acknowledge that I'm new to Win 7 (or Vista for that matter) - but I've set up a lot of networks. Just bought a Dell Alienware 64 bit - it came with Vista, just "upgraded" to Win 7. Now get no connections available all the time (almost) for wireless adapter (broadcom 802.11n) on two different wireless networks that currently connect to various XP systems & used to connect to this system with Vista.
I said almost because on a couple of occasions (once when I turned off both Norton & Windows security) & restarted system, the access point was detected, I was allowed to connect - verified I could move about the web. At this point I assumed I had some kind of firewall blocking issue - but to be sure, restarted the system (no changing or enabling anything) and upon restart was back to the usual issue "no connections are available"
The wired Nic works fine.
Again, the problem started after installing Win 7 Pro (Custom/clean install). I have the latest adaptor driver from Dell. The access point I'm trying right now is from ATT - "2 wire 2701 HG-B (g mode). The other access point is a Linksys WAP54G.
Also after installing Win 7, it seems I now have a "Microsoft Virtual WiFi miniport" - not sure what that means. Again the XP systems in this office all connect fine. There's more things I've tried (uninstalling adaptor (in manage devices, manually adding NW, etc. all to no avail) - I'm now stuck. Anyone with ideas?

 

[SanDiego7697]

Update to this post: found that wireless connection worked after also connecting wired Nic. It then found wireless AP. Could then disconnect wired connection cable & still maintain wireless access. However, when power cycled, the connection couldn't be found again until cable reconnected.
Then "Disabled" the wired NIC & the wirless connection comes up fine (even after power clycling). Now suspect it's some kind of IP routing issue (have no idea how or why - but perhaps a "persistent route" was intitially created. Will look into later tonight

 

[SanDiego7697]

Solution:Had to disable Device sleep on disconnect

This is just to post the solution. When installing Win 7 (pro - 64) it updated the nVidia Ethernet (wired) NIC diver and enabled the parameter "Device Sleep on Disconnect". By disabling this setting, the wireless auto connects fine in both locations (and when an Ethernet cable is connected, the wireless goes off per our desired settings).

 

[chev65]

Yes those power settings have been causing all sorts of problems with network connections. Thanks for reporting in.