event ID 8003 windows server 2003
try resolutions mentioned in these Microsoft articles and check again:
Hundreds of Event 8003 errors on layer 3 network
There will be no consistency about which machine reports that it thinks it is the master browser. This is a symptom, not a cause. When a machine cannot obtain a browse list (because it cannot find a master browser), it assumes that browsing has failed. It then declares itself the master browser to force an election. That is how the system works. The machine which actually triggers the election is not the problem.
Browsing is an NT legacy app, so it really has nothing to do with AD or DNS. Basically it relies on Netbios names and LAN broadcasts, and originally only worked in a single segment. To enable it to work across routers you need to have WINS and Netbios over TCP/IP, and you need all machines to register with WINS. WINS allows the master browsers to communicate directly (rather than through broadcasts) by converting names to IP addresses.
First up, make sure that all of your servers have Netbios over TCP/IP enabled. If any of them are multihomed, make sure that only one interface has NBT enabled. Apart from that, debugging browser problems is still the same as it was in NT. The standard tool is browstat. The standard decription of browing is KB188001 and the standard troubleshooter is KB188305.