I've cleaned a computer of viruses and malware. The computer is now working great. All software appears to be running fine. This computer is running Avast Antivirus. The problem is that I noticed that Avast cannot update it's virus definitions. I would think this an Avast software problem except that I also noticed that Malwarebytes and Superantispyware (these are there just temporarily) cannot update their definitions either. This tells me it is a computer problem. Apparently the port they use to update is blocked. I don't know how to find out what port or how to unblock. I did notice that I can update in Safe Mode. I looked at the processes when in normal mode and nothing stands out. Any ideas? (I've reset the Tcpip stack and reset the winsock catalog, I've checked the hosts file and it is clear).

You can change which ports are open and which are closed by going into the firewall settings on your computer.

To do this you simply open up your windows control panel and go to the firewall settings. Then click on exceptions and click add port to tell Windows to allow information to cross through that port in your firewall (of course all this requires admin rights, but I'm assuming you have them). You could also just check the name of the program and Windows will let everything about that program pass through your firewall whatever the port may be.

I don't know anything about those programs but you could go to their website and somewhere on them it should give information about what ports they require for certain actions/uses of the program.

Check again your FIREWALL SETTINGS. You might have disabled your antivirus ports there.

going into the firewall settings on your computer.

Check again your FIREWALL SETTINGS.

There must be an echo in here

Sorry about the echo. If that did not solve your problem then please be a bit more specific in your question. I think I know what your talking about but I'm not sure anymore.

I assume you've checked windows firewall.

I would uninstall all antivirus/malware/adware programs (if only to resolve the issue) and install comodo Internet Security Suite. It will offer an alternate DNS server. It also shows the status of ports.

Post back here if you do not resolve the issue.