For that type of problem you can read the "Cannot Leave Homegroup" thread below which talks about fixing the same problem.
This will also fix problems related to joining the Homegroup
, as it seems this is a big problem with wireless machines trying to join the Homegroup.
I will show you the more direct approach to fixing the problem here. This is another Windows 7 bug apparently so you need to remove some files from the Peer Networking folder in order to fix this problem. In order to see the AppData folder you will need to go into Folder Options in the Control Panel and put a check mark to "Show Hidden Files and Folders".
The fix for this problem seems to be Deleting all files
which reside in PeerNetworking "second picture" at> C:\windows\serviceProfiles\LocalService\AppData\Roaming\PeerNetworking After this, you must also leave the Homegroup from all machines and create a new one. It sometimes works best to create the new Homegroup from the wireless machine and join from the wired machines.
Once everything at peer Networking Grouping is running you may also need to do this... Start the Task Manager Click on the service Tab Find the "HomeGroupProvider" and then stop the service. You may need to go back into services and enable Peernetworking again after the fix. Don't forget to restart all machines making the adjustments. Cannot leave Homegroup