Windows 2000 Server Browsing Problems

I am experieng trouble with browsing on my Windows 2000 server network. The server is running Windows 2000 with Service Pack 2. It is running WINS, DHCP, DNS, and Active Directory. The clients are correctly getting all the IP information but are getting event id errors 8021 and 8032

Event id: 8021
Source: Browser
Description: The browser was unable to retrieve a list of servers from the
browser master on the network \device\.
The data is the error code.
Event id: 8032
Source: Browser
Description: The browser service has failed to retrieve the backup list too
many times on transport of . The backup browser is
stopping.

The clients are a mix of Windows 2000 machinesand Windows 98 machines. They are experiencing intermittent connectivity problems, i.e. loss of ability to print, and the ability to access the server resources such as files- although I can still ping the server. The Windows 98 machines are also having intermittent trouble logging in when they boot up the computer- they get an error message saying that the domain password is incorrect or the domain server is unavailable.

I believe it is a browsing issue. I changed the server registry setting ISDOMAINMASTER from FALSE to YES. However I am still experiencing problems.

Any help you may be able to give me is GREATLY appreciated. This problem has me boggled.

Thanks