I have Plantronics Audio 995 wireless headset (for couple years) and use it to listen to music. I use Windows Media Player with it, since after some poking at start it worked best with media buttons on the headset.
Recently though it randomly stops reacting to bulk of button presses from headset. It still reacts to some of commands — for example "next track" stops working, but holding "next track" is processed correctly as fast forward. So I don't think this is hardware issue with headset — the button press is being registered and sent to computer.
Which leaves software issue, but how do I debug this on computer side?..
The only other headset–related software running is Skype, but it is configured to use different device (web camera + main speakers) and exiting it doesn't fix the issue.
Computer is self–built desktop, Windows 7 x64 Home Premium, fully updated, etc.
No headset drivers (I don't think there even were any), note it's not bluetooth — just has its own dedicated wireless dongle.
Shell extensions, as requested in comments (non–MS, duplicates truncated):
Bluewire General Property Sheet
BTSync
ComposerSetup
IcarosPropertyHandler.IcarosPropertyHandler
Microsoft XPS Rich Preview Handler
paint.net Shell Extension
TortoiseSVN
UnlockerShellExtension
AppShellPage Class
Ath_CopyHook
ContextMenu Class
FTShellContext Class
CDISPSHELL Extension
Comodo AntiVirus
DropboxExt
7-Zip Shell Extension
GraphicsShellExt Class
LastPass Toolbar
LastPass Vault
KbLogiExt Class