Windows Live Mail 2012 problem

[#1]

Hi to all. As per the thread title, I'm having problems receiving email from Plusnet. I'm getting the following error notice:
Unable to send or receive messages for the Plusnet account. The email server returned an error.
Server Error: 0x800CCC90
Server Response: -ERR Cannot connect to POP server 212.159.8.81 (212.159.8.81:110), connect error 10013
Server: 'mail.plus.net'
Windows Live Mail Error ID: 0x800CCC90
Protocol: POP3
Port: 110
Secure(SSL): No
It's not only my Plusnet account that's affected, I also have O2 and Gmail accounts. My Outlook accounts are, perhaps unsurprisingly, unaffected. These problems started shortly after installing VPN software (Tunnelbear) but even after uninstalling it, I still have the problem.
I've had a look at Windows Firewall - all three Windows Live Communications Platform options are ticked for both private and public networks and I've also just ticked the Mail and Calendar option for both types of network, although I'm not 100% sure I should be messing about with it if it's not already allowed.
Hope I've covered everything in order that someone may be able to help, but perhaps I should mention that I'm running Windows 10. 
Thanks in advance
Graham

[#2]

What response do you get if you open a command window and type telnet 212.159.8.81 110 (You may need to enable telnet before trying this)
Also try tracert 212.159.8.81

[#3]

Hi pwatson.
The telnet command comes back with:  ERR  Cannot connect to POP server 212.159.8.81 (212.159.8.81:110), connect error 10013. Connection to host lost.
The tracert command reports: 1 General failure.
As an addition to my OP, I should also say that all settings on WLM are correct.

[#4]

Looks to be nothing to do with Live Mail then - This is a problem with the networking setup of your machine.
Do you have a restore point prior to the installation of the VPN software?  Have you installed any anti-virus recently software?

[#5]

Ok, following on from what you appeared to be suggesting, I've done a system restore, checked and WLM appears to be working properly again. I've also re-updated my Avast Pro app that I remembered prompting me to update immediately after installing TunnelBear, and reinstalled TunnelBear (restarting and checking at each step) and, apart from a small hiccup, which I solved by closing and restarting WLM, it still seems to be working properly. I've also done the Telnet thing ("Ok hello there") and the tracert command has completed too. So everything seems fixed. 
Hopefully I won't have any more problems (famous last words) - thanks for your help.