Wireless network trouble

Wireless network trouble - no wireless when ethernet cable is plugged in

Hey all

I've been roaming the net for two days in a row but I can't find any answer to my problem, so here's my first ever shout for help on a forum:

A while ago, i read something about the possibility to use your pc as a wireless accesspoint for other pc's (internet connection sharing on an ad hoc network). I thought this being very useful so I tried it and it worked immediately. About 15 minutes later my pc decided to go to sleep (because I wanted it to in any other situation) so the connection fell away. Ever since I have been unable to create any wireless network, and after a while I discovered that I can't actually detect any wireless network in range as long as the ethernet cable is plugged in. As soon as I unplug it available networks pop up. This is not so much a problem as I would like to get the ad hoc network to work again.

Here's what's up with my pc and what i've tried:

-My pc is a HP compaq 8510w workstation with a intel wireless wifi link 4965AGN module, and running windows 7 professional (64-bit)
-It didn't fall down or i didn't bump it or anything recently
-I was sharing my internet connection (cable) through an ad hoc network (wireless) and it worked fine on the other laptop when my pc went to sleep and the problems started
-The main problem is that I can't create a new wireless network anymore, when i do so, windows says "Could not create [network]"
-So I tried restarting for several times, turning off my wireless adapter and back on, I searched the internet for solutions, like a driver update, I reinstalled the drivers for all wireless and bluetooth adapters, I went looking in the bios and turned off the wireless radio and back on and after all this i found out that, if i unplug my ethernet cable, wireless connections do show but the real problem remains. I also went through thousands of setting of the adapters and also my firewall but no results so far.

If anyone knows how to solve this, I'd be enormously thankful! Or if you need more information, let me know!

Greetz!