Dear Adam, thank you for following up and for your support.
1- in the my documents > PGP folder, I found 4 keys pubring, pubring-bak, secring, secring-bak. Trying to import any of them gives " Encryotion Desktop is unable to import any keys, certificates, or groups from the selected file".
However, if I double clicked on the files of either pubring-bak or secring-bak, the files are opened successfully and new entries are added in the PGP Keys section. Both contain the same credentials including name and email, they both are verified too.
I went back to the PGP Disk sectino, clicked on the encrypted drive, and clicked "mount", same error message I used to have.
I clicked "Add user key", then from the All keys dropdown list I selected pubring-bak, the key appeared with a green tickmark next to it, I double-clicked it, it was copied from the "key source" column" to the "keys to add" column". Then I clicked Ok, but I got the same old error message: " 'USERNAME': there was a problem creating this user".
2- I checked the logs up to 7 days ago, and they contain NO mention of keys whatsoever. What I see is all or some of the following lines:
02:26:10 ----- Encryption Desktop stopped -----
02:27:33 ----- Encryption Desktop started -----
02:27:33 Encryption Desktop 10.3.0 (Build 8741) (8741)
02:27:33 Today's date is Friday, August 15, 2014
02:27:33 Email Warning Email proxying has been disabled by the user
02:27:33 PGP Info Setting logging level to: normal
In the day the problem started, the log is:
00:04:59 PGP Info Initiating daily maintenance procedures
00:04:59 ----- Encryption Desktop continuing -----
00:04:59 Encryption Desktop 10.3.0 (Build 8741) (8741)
00:04:59 Today's date is Monday, August 18, 2014
15:28:39 ----- Encryption Desktop started -----
15:28:39 Encryption Desktop 10.3.0 (Build 8741) (8741)
15:28:39 Today's date is Monday, August 18, 2014
15:28:39 Email Warning Email proxying has been disabled by the user
15:28:39 PGP Info Setting logging level to: normal
15:28:39 Email Warning Email proxying has been disabled by the user
15:28:45 PGP Info Initiating daily maintenance procedures
3- I only had one key before, which is the key I see now after I double-clicked the pubring-bak file.
I hope this info helps