I have the same issue, and I have never used the "screen lock" option in
the start menu.

Mine is caused bythe Nvidia driver, from vendor, for my Quadro card,
does not play well with TDE.

You don't mention video card info or drivers, could help.

ps, my solution was to rename the executable responsible:
/opt/trinity/bin/kdesktop_lock to kdesktop_lock.bk

Greg M
On 02/02/2017 08:09 AM, Baron wrote:
> Hi Guys,
> 
> PCLOS Trinity 14.0X
> 
> For the past few days I have been getting a "Session locked by user" 
> message with only user can unlock this session.
> 
> I can enter my password and get in with everything working OK.
> If I reboot, hard reset, I don't get this message again when I login.
> I may not see this again for two or three days, and then its back.
> 
> I don't normally leave the computer switched on so I might restart the 
> computer twice a day.
> 
> Anybody any clue as to why this has started to occur.
> 
> Thanks in advance for any help.
>