Sharky7Sharky - thanks for response, but none of the suggestions in the link provided work for me. I have also uninstalled and reinstalled avast! Pro/Suite, per avast support suggestio, with no success. I have narrowed this down to a happening when pc resumes from sleep mode - not sure what that means tho. I don't share files, etc. so all settings on wireless adapter, avast! firewall, etc have been to disable Netbios over TCPIP, blocking Windows Networking In and Out Packets, all with no success in eliminating Event Error 4311 NetBT from happening.
However, I found one thing that seems to stop the NetBT error and I feel this is my main problem. I turned off "sleep mode" in Power Options, setting it to "never". Since I did that, I haven't seen the error. Some way, when my pc awakes from sleep mode, something (maybe avast!) is trying to make a connection and causes the error. With sleep mode shut off, no such connection is attempted and no error in Event Viewer shows up. Hope this might help others who might be having similar problems.