Odd characters

Hello, These odd characters appear from time to time. They aren't hugely annoying, so I've never done anything about them, but now I'm trying to communicate with someone who needs me to see something I can't because of them. Any clues what to do to get rid of whatever is doing it?


http://gyazo.com/836236e365234698e604ab61e33e3cd6

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 8.1 Pro, 64 bit
Processor: AMD FX(tm)-8350 Eight-Core Processor, AMD64 Family 21 Model 2 Stepping 0
Processor Count: 8
RAM: 8091 Mb
Graphics Card: NVIDIA GeForce GTX 750, 1024 Mb
Hard Drives: C: Total - 953340 MB, Free - 875751 MB; E: Total - 29996 MB, Free - 24399 MB; F: Total - 180464 MB, Free - 97843 MB; G: Total - 28003 MB, Free - 27129 MB; H: Total - 753870 MB, Free - 752366 MB; I: Total - 199996 MB, Free - 150226 MB;
Motherboard: ASUSTeK COMPUTER INC., M5A99X EVO R2.0
Antivirus: Windows Defender, Disabled

(Windows Defender isn't disabled)