User account locking automatically

> When I am idle for about 10 minutes, my desktop disappears and another
> screen
> appears saying that my user account is locked.
>
> I am not using a screensaver and I have set my power settings to 'Never'.
>
> I made these settings about 3 weeks ago and, until today, I have not had
> this happen before.
>
> The only change that I made between then and now is that I installed some
> software yesterday.
>
> Because of this, I am considering uninstalling that software.
>
> However, I am not sure what to do next.
>
> Also, if this is occuring because of a setting that I can change, I would
> prefer to just make that setting change rather than uninstalling the
> software.
>
> Does anyone have any suggestions?
>
> With appreciation,
> Charles