What do u mean by group ? do u mean a domain ? or a workgroup ?
if a workgroup ,, I think u have to restart the PC and wait more than 15 minutes to judge the connection ..
You also can check to search for other PCs using their names ,, or using their IPs ? if u still can't find them ,, try to ping their IPs or their names ,, to see if you are really connected to them ,,
also u have to ensure that they are installing file and printing sharing .. Mohamed Farid
Know Me No Pain , No Me Know Pain !!!