When I open Windows explorer, I cannot see my Imac computer (which is part of my Workgroup) in the Network folder. However, when I click on Recent Places, and then double click a folder in Recent Places that is on the Imac, that folder does appear and I can then access all other folders on the Imac by clicking on the Imac in the address window. At this point, the Imac appears in the drop down of the Network folder in the left pane, but does appear in the main window when I click on the Network folder in the left pane.
I have had this Windows 7 laptop for several months, and this problem only started a few days ago. Before that, the Imac usually showed up in the Network folder. The only change I have made to the computer recently was adding a User. I deleted that User this morning, just in case that would fix the problem. It did not, but I should add that I have not restarted the computer since I deleted that User.