Have you tried releasing and renewing your network adapter? In your RUN box, type CMD, then enter. A command line window will open. Starting at the blinking cursor, type: ipconfig /release then enter. Hit the F3 button and backspace to the 'L' and type over the 'L' so that it reads 'renew'- should look somthing like this C:\XXXXX>ipconfig /release ENTER. Then C:\XXXXX>ipconfig /renew ENTER. Note the space before the forward slash.
I'd also double check that your workgroup name at home hasn't changed- right click My Computer, left-click properties, left-click Computer name, left-click the ''Change'' tab, and see if you are in fact a part of your home work-group, or if the workgroup name has somehow automagically changed- every now and then, my laptop workgroup name changes back to ''Workgroup''. Turn off all firewalls like ZoneAlarm while trouble-shooting. If you do connect after troubleshooting, then lose your connection, check your firewall configuration; actually, I'd simply turn off ZoneAlarm or another other software firewall first before anything else. Could be somethin as simple as that. Hope this was of some help. Good luck.