Eddie:
This can be caused by a couple of things.
1. The shared folder does not have your Windows user in the Share/Security permissions.
If you have the right shared permissions check number 2
2. Firewall exceptions for SQL BROWSER, and SQLSERVR
In the Windows Firewall exceptions add C:\Program Files\Microsoft SQL Server\90\Shared\sqlbrowser.exe and C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Binn\sqlservr.exe
3. Last but not least, test your credentials on the server from the client machine having the problem by going to Start > Run > type
\\servername then press enter.
If you are prompted to log in, put in your Windows Server credentials and log in. Then try to Synch again.