This means that the MAster browser list is not available to client systems.
Most common causes are as follows:
**A failed server - Reboot you Browser master(usually your PDC, but rebooting any DC will reinitiate a browser election)
**A BDC was promoted to a BDC but does not have the browser.dll installed.
**No WINS server installed or it is not functional
**Browser service may be removed from NT server - check the service list for installation and operation.
**Servers have been configured not to maintain browser lists -
If you don't understand Browser operations check out Technet articles Q102878, Q120151, Q130401.