cannot mute internal speakers

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows XP Home Edition, Service Pack 3, 32 bit
Processor: Genuine Intel(R) CPU T2300 @ 1.66GHz, x86 Family 6 Model 14 Stepping 8
Processor Count: 2
RAM: 2037 Mb
Graphics Card: Mobile Intel(R) 945GM Express Chipset Family, 224 Mb
Hard Drives: C: Total - 95385 MB, Free - 10646 MB;
Motherboard: FUJITSU, TRUFF01
Antivirus: AVG Anti-Virus Free Edition 2012, Updated: Yes, On-Demand Scanner: Enabled

When I plug in my headphones, my internal speakers in my laptop do not mute. I can no longer listen in privacy.

Any suggestions?

Tnx,

mercystreams