Ok I've seen these types of problems many times in the past and there are a few solutions that should help. No guarantee's here because when the Homegroup goes south it really goes down the tubes.
First you will want to go into
C:\windows\serviceProfiles\LocalService\AppData\Roaming\PeerNetworking and delete all files in this folder, the picture below shows the path and what these files look like, simply delete all files you see there as these are the source of many problems, such as not being able to leave the Homegroup or not being able to rejoin, etc.
In order to see the AppData file etc. you will need to go into
Folder Options in the Control Panel and enable the setting that says
"Show hidden files and folders".
You will need to do this on all Homegroup machines. After that you will want to
leave the Homegroup on all machines, then reboot all machines and then create a new Homegroup rejoin from all machines.
You should also ensure that the following services are running.
In order for the HomeGroup networking feature to be working, there are certain Windows services that need to be enabled and running. If you used a program to disable services or manually disabled them, it may be causing the problem.
The services that need to be turned on are listed below:
•DNS Client
•Function Discovery Provider Host
•Function Discovery Resource Publication
•Peer Networking Grouping
•HomeGroup Provider
•HomeGroup Listener
•SSDP Discovery
•UPnP Device Host
You can turn on the services by clicking on Start and typing in “services” and then clicking on Services.
Ultimate Troubleshooting Guide for Windows 7 HomeGroup Connection Issues - Help Desk Geek
