Windows 7: Sound volume goes down to 5% after connecting removable device

Hi
I recently noticed something very weird: every time I connect a removable device such as USB flash drive or external HDD or even my smartphone, the sound volume goes down to 5% but only for the browser & mediaplayer. I can change the sound volume using volume mixer but it's annoying doing so every time I connect something to my PC.
I reinstalled the drivers for my sound card & for every device I usually connect & also I reinstalled the browser(Opera browser) & Winamp without luck.
Also, I had some problems in the past that might be related to this one. After installing SP1 every time I logged into windows I was notified that Audio Service is not running although it was running. (solved this one).
Another problem was related to USB removable devices. Apparently Windows was unable to assign letters to all my removable devices, even if I manually assigned a letter to a certain device. I didn't solve this one, however I use USB Safely Remove to assign letters and it seams to be working fine so far. ( Windows 7 does not assign drive letters to external HDDs )
Any ideas?

Yeah, well it's a little bit too late but I solved this.
Control Panel -> Sounds -> Communications tab ->When Windows detects communications activity -> Reduce the volume of other sounds by 80% was checked

I switched to Do Nothing and so far it seams to be working.

Don't know exactly why hard drives were detected as communication devices but my guess is that this has something to do with Winamp/WMP library since I am always asked by these 2 apps to add the new device to Library, even if there's no audio/video/image file on it.