I don't think this will have occurred for many people but stems back to when I was using Windows 7. I used to have the accessibility keyboard opening on start-up which was configured to happen via 'msconfig'.
Since upgrading to Windows 8 and Windows 10, it seems that during one of these upgrades the opening of this exe on startup has been somehow inadvertently attached to the playing of a sound in Windows and is somehow embedded in the registry to do this.
I'm only posting this now as since the advent of Windows 10, these registry settings seem to have been attached to my Microsoft account and now all of my devices are now doing this.
So the on-screen keyboard filename is 'osk.exe'. I did a quick search for this in the registry and only one key appears to contain this:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Internet Explorer\LowRegistry\Audio\PolicyConfig\PropertyStore\e134fd88_0
The key value is:
{2}.\\?\hdaudio#func_01&ven_1013&dev_4206&subsys_106b0100&rev_1003#{6994ad04-93ef-11d0-a3cc-00a0c9223196}\espeakertopo/00010001|\Device\HarddiskVolume2\Windows\System32\osk.exe%b{00000000-0000-0000-0000-000000000000}
Clearly this key is something to do with the audio settings of my machine, although its in the Internet Explorer section of the registry, it clearly is the offender. My question is, what can I change this to? What should the value of this temporary key be, to prevent this occuring?