Hi cletus76,
Welcome to the HP Forums!
This is usually resolves auto reducing symptoms, but is still worth a shot.
Control Panel > Hardware and Sound > In the Sound Category look for Manage Audio Devices
On the Communications tab try selecting "Do nothing".
To test to make sure that it is not a physical volume up button issue, you should see if there is an option to disable the volume buttons in the BIOS. If there is then this is the path to take.
Hold the power button for at least five seconds to turn off the computer.
Turn on the computer and immediately press the F2 key repeatedly, about once every second.
In the BIOS you will need to use your arrow keys to move around, as the mouse will not function. Press the arrow keys until System Configuration is highlighted, and press Enter. Then you will need to look for Button Sound, or something similar. It is probably set to Enable, if you press Enter while this is highlighted it will turn to Disabled. At this point you will want to find the option for save, and exit.
When in the Windows environment, see if the volume issue still occurs. If it does you will want to contact technical support at 800-474-6836. If you live outside the US/Canada Region, please click the link below to get the support number for your region http://www.hp.com/cgi-bin/hpsupport/index.pl, for any repair or replacement options.
Regards. :)