Scrolling mouse sets windows sound volume

Suddenly, when I use the scroll wheel of my mouse, it changes the windows sound volume level.

I have a HP DV6-2030SD laptop with Windows 7 64 bit and a Zolid p50622 mouse. When I use the scroll function of the mouse pad of the laptop, it does not adjust the sound level.

I don't have any special mouse drivers installed, just the standard windows drivers. When I scroll, I see the HP sound level screen:

It doesn't do it always, but when it does, it prevents the current window to scroll, which is really annoying. Rebooting doesn't help. I've tried to put the USB dongle in a different port, but this doesn't help either.

Any advise on how I can fix this?

Edit:

• I noticed that the navigation buttons (previous and next) also don't work when it happens.
• Removing the windows device from the device manager didn't help

I found the problem. It has to do with the DPI switch of the mouse. It has been pushed into the casing of the mouse which made it act like that. After freeing the button (and reinserting the batteries) it worked again.