Blocking Mozilla programs

Hello Anthony,
I apologize for the difficulties caused to you. Please confirm whether you are using trial version of AVG Internet Security 2017 in your PC. If so, please configure firewall settings as per the below steps and check the status.
Open AVG  -> Internet Security -> Menu -> Settings -> Components -> Firewall -> Customize ->Policies->System Rules->Enable the 'Allow windows file and printer sharing', enable the 'Allow remote desktop connections to this computer' and also enable the 'Allow stealth mode for public networks'. Then click OK to save changes. Then please click on Network profiles tab -> change the network profiles from Public to Private and click OK to save changes.
Keep us informed about the status.

My main computer is a Windows XP SP3 machine. I have not updated it as I have an essential piece of software that does not function on later versions and is no longer supported.
When AVG Internet Security was updated recently I found that I could no longer load either Firefox or Thunderbird. The processes show up, but no window opens.
I have found that switching AVG off allows the programs to load up correctly, but understandably I am not happy doing that.
I have checked the firewall settings, and it says that both programs are permitted.
I have spent several hours trying to fix this, including returning to earlier Restore points, shutting down, switching off, removing Firefox and reloading it (a long process here as we have very slow broadband)
Any suggestions?

Hello Anthony,
I apologize for the difficulties caused to you. Please confirm whether you are using trial version of AVG Internet Security 2017 in your PC. If so, please configure firewall settings as per the below steps and check the status.
Open AVG  -> Internet Security -> Menu -> Settings -> Components -> Firewall -> Customize ->Policies->System Rules->Enable the 'Allow windows file and printer sharing', enable the 'Allow remote desktop connections to this computer' and also enable the 'Allow stealth mode for public networks'. Then click OK to save changes. Then please click on Network profiles tab -> change the network profiles from Public to Private and click OK to save changes.
Keep us informed about the status.

Hello Anthony,

We are happy to hear that the issue is resolved.  We appreciate your time and co-operation. The status we asked is, if you are able to load Mozilla Firefox and  Thunderbird after changing this firewall settings from AVG.

My version is V 17.7.3032 which was uploaded automatically a couple of days ago, after which the problems occurred. The steps were not as described above but I did find the settings and changed them. The problem appears to have been solved and the time taken to be ready after switch-on has noticeably lessened. What do you mean about checking status?