Unable to recieve public key

[DB Troll]

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Lately I have had some signed messages that lock the system for 2-3 
minutes with my firewall on. If I shutdown the firewall this does not 
happen but all of the messages still take a bit before enigmail shows 
Unverified signature, click pen icon. When I click icon it of course 
opens another window to import public key. I say OK the it comes back 
with yet another box stating
Unable to receive public key
gpg: requesting key 0x49E...... from wwwkeys.uk.pgp.net
gpg: no valid OpenPGP data found
gpg: Total number processed: 0
Anyone advise on this.
TIA
David








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