I bought an I730 off of ebay that came with WM5 installed. For about a month, the WiFi worked really great. I could connect to just about any unsecured hotspot with no trouble. I could also connect to both of my Wireless Access Points here at the house one on channel 11 and one on Channel 6. All security is turned off.
Then one morning, after I left it on the wall charger with the WiFi on overnight, I noticed that it was connected to the Access Point that has a weak signal, even though the other one was only ten feet away. A nearby laptop was still connected to the stronger signaled Access Point. I hadn't made any changes to the phone for three days before this happened.
Ever since then, the wifi hasn't been very good.

It connects to the weak signaled one quickly and with no trouble, but won't connect to the stronger signaled one, and just shows "Available, Connecting, then back to Available."
Same with the public hotspots that have no security on them. I can see them, but I just can't connect.
Here is what I have done so far:
Hard Reset the Phone
Used MRailings hack cab
Increased Max TCP Connect Retransmissions to 10 from the default of 2
Reduced the WiFi scanning time to 30 seconds from the default of one minute.
Since one WAP works and the other doesn't, I have compared the two looking for a clue:
Updated the Netgear WGR614v6 firmware and then rolled it back.
Made sure that both routers had as close to the same settings as possible.
Studied the working one. It is a Buffalo router running Tomato firmware, so there is a lot to see, vs. the Netgear where there isn't much.
No firewalls running in either router.
Turned DHCP on and off while assigning IP addresses as needed -- non-connecting router will not assign phone an IP address.
Changed the Buffalo to Short Preamble means to connection by the phone and chaning it back to Long works fine. No setting for that on the Netgear.
Meanwhile the laptop connects just fine to the hotspots and both routers. I have noticed that it takes about 20 seconds of trying before it connects to the stronger signaled Netgear, though. It's an old "b" type DLink card in the lasptop and I am using the driver to connect rather than the Zero Wireless thingy in XP.
I think this is kind of weird. If the Wifi circuit was burned out or even if it was getting weak one would think that the sensitivity would go down and it would only connect to strong signals.