Why is this volume control panel appearing on screen?

Recently, a strange volume control panel has begun appearing on my screen. Right in the middle of it. The panel is not the normal Windows one. My mouse cursor just moves behind it. Adjusting the volume manually doesn't change it at all. I updated the drivers for my processors, audio, monitor, and graphic card,... show more Recently, a strange volume control panel has begun appearing on my screen. Right in the middle of it. The panel is not the normal Windows one. My mouse cursor just moves behind it. Adjusting the volume manually doesn't change it at all. I updated the drivers for my processors, audio, monitor, and graphic card, but nothing seems to help. It seems to come and go. Strangely, it doesn't even really appear else where. I tried to get a screen shot of it, using prt Scr and photoshop- but the panel didn't appear in the image. The panel is mostly black and gray with an orange volume control in the middle, but has no real way of interacting with it. It says 1440x900 -60Hz at the bottom.

My system is a 32-bit Windows Vista, Graphics card is a ATI Radeon HD 4300/4500 Series. Monitor is a HP w1907 Wide LCD and it Realtek Audio devices. Intel(R)Core(TM)2 Duo CPU E4500 processors. Any ideas?
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