Weird Windows Fixes: Removing corporate wireless restrictions completely : "The policies of your network prevent the creation of ad hoc (computer-to-computer) networks. For more information, contact your system administrator."

1: open services.msc as administrator, scroll down to WLAN AutoConfig:

and stop the service for now.

2: Open regedit.exe as administrator and browse to
back up the key and delete it, change the permissions on the Wireless folder above the GTPWirelessPolicy and take ownership of it and give full permissions only to yourself and administrators.

3: GO to the key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\GPExtensions\{OACDD4OC-75AC-47ab-BAAO- BF6DE7E7FE63}

and delete it, change the permissions on the GPExtensions key as well, giving ownership to yourself and administrators only.

4: Go to the folder
C:\Windows\wlansvc and remove a .tmp file that contains wireless policy.
Change the permissions of the wlansvc folder to only give ownership and editing rights to yourself.

5: open services.msc and start WLAN AutoConfig
You should be able to establish an adhoc network now and all your wireless related group policies will also be gone.