The following seems to have got me running normally again. Working on the theory the keyring file was somehow corrupted, I deleted the keyring file...
rm ~/.local/share/keyrings/login.keyring
...and rebooted. A new keyring file has been generated and everything looks good for now!
The following seems to have got me running normally again. Working on the theory the keyring file was somehow corrupted, I deleted the keyring file... share/keyrings/ login.keyring
rm ~/.local/
...and rebooted. A new keyring file has been generated and everything looks good for now!