Weird graphics glitch when using Fn volume/brightness hotkey

[dsirus5]

Hi everybody! I'm a long-time fan of Linux Mint - been away for awhile, just installed the Cinnamon flavor of Nadia on my machine, and I'm loving it!

I've only got one small problem with it so far: When I use the Fn volume or screen brightness hotkeys...they work, but a weird white rectangle with vertical blue lines going through it appears in the top-left corner of the screen. The volume hotkeys also display the standard "speaker" graphic with a bar showing current volume level, while the screen brightness hotkeys display nothing else.

Just wondering if anyone else has had this problem, or maybe has a proposed solution. Will try to post a screenshot in a bit. Thanks!

[dsirus5]

...well, shoot: it doesn't appear in my screenshots