I have already gone through a bunch of questions here on superuser regarding ad hoc connectivity, but couldn't find one that covered my situation.
The Setup
I have a Windows 7 laptop that we want to enable as a wireless gateway at a conference booth, allowing people free access to our online product while they near the booth (since we would identify the laptop as the gateway).
Anyway, I've plugged in a USB NetComm NP545 wireless adapter into the laptop (which already has an Intel PROset built in) and configured a connection on this adapter to act as an ad hoc network using WPA2 security.
I've also enabled internet sharing on the connection setup on the primary adapter.
The Problem
When it came to testing the ad hoc network, we've encountered a variety of problems.
Firstly, two different Android devices (4.0 and 2.3) and an iPad cannot even discover the device.
Secondly, a Nokia N97 and another laptop can discover the network, but cannot login.
Best Answer
I had the same problem. Phones have a hard time connecting to ad-hoc networks. An access point works best. Try Connectify. I use it and think it is quite good. There is another Superuser question which explains how it works.