Might be an issue with lightdm, or whatever they use on ubuntu mint 
these days.  Maybe try a different login manager like gdm (if usable 
still?) or kdm?

I'd say ssh in and see what syslog or x logs show.

I have/had a weird issue like this using lmde with mate, where recently 
my trackpad would stop working on me after about a minute into using the 
desktop from lightdm login manager.  Plugging in a usb mouse would work, 
but quite annoying to now have to carry a mouse.  I tried fiddling with 
the trackpad settings, seemed something related to the desktop is 
"turning it off", but I've no idea what, and see no dmesg/syslog output 
occur when it does.  Not sure at all if this is same since your issue 
seems to be lightdm, but maybe some regression in the desktop system 
since cinnamon and mate seem to share gconf settings.

Quick fix was moving to kde, as cinnamon already proved far too buggy 
for use, and apparently so is mate as that was the final straw.  I 
migrated from mate to kde on my desktop as well as mate provided all 
sorts of new and not-so-interesting bugs there as well.

-mb


On 12/28/2014 07:26 PM, koder wrote:
> I would appreciate some guidance troubleshooting a problem on my 
> computer.
>
> I am running Mint 17.1 on a relatively new Dell XPS i7 box.
>
> Since I installed Mint I have been having instances of arriving at the 
> login screen and the USB keyboard and mouse are not recognized.
>
> I am not able to use the mouse to place the cursor in the login field 
> for password entry.
>
> The instances are now three or four times in succession per login 
> session.
>
> Every time I boot up the system goes into the GRUB boot menu and I am 
> able to move the cursor around and move amongst the menu choices.
>
> I have looked over my dmesg output for successful and unsuccessful 
> boots and not received much enlightenment. They are about 950 lines of 
> text. I suspect I ought not to post them.
>
> Any suggestions?
>
> Harold
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