A couple of things to check with that.
First get "Microsoft Fix it 50203" from http://go.microsoft.com/?linkid=9662461
Reboot see if that worked.
- First go to c:\WINDOWS\system32\drivers\netbt.sys and make sure that file exists. It it doesn't, find your Windows XP SP3 installation disk and (Start | Run | sfc /scannow) to replace system files that have been changed or deleted (typically it seems are afd.sys, netbt.sys and tcpip.sys these days).
- Then go into Device Manager (Start | Run | devmgmt.msc) and under the View tab, select Show hidden devices. Scroll down to and expand Non-plug and play Drivers. Make sure that NetBios over Tcpip is present. If it is present, double-click on that entry and select the Driver tab. Make sure the current Status is Started and Startup type is System (from the drop-down menu). If it is not present open the Registry editor (Start | Run | regedit) and go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetBT . If that registry key doesn't exist you'll probably want to export it from an existing XP set up and import it into the problem machine.
Reboot and scan with updated AV software, MalwareBytes and Super Anti-Spyware. Hope this helps.