Everytime i play anything on my computer there is no sound but the sound works when i connect speakers or earphones??? any help would be greatly appreciated

When I plug in my headphones into my computers speakers there is a loud buzzing in the left ear piece. The headphones work fine when I use them for anything else. And when there’s no headphones in the speaker, there’s no buzzing. I just bought these speakers. So why when I use headphones is there a loud buzzing in the left ear piece and how do I fix it?

Basically i want my computer speakers, which have a 3. 5mm connector like headphones have, plugged into my TV. But i still want the TV speakers to be working while the computer speakers are plugged in.

I have an MP3 player (Creative Zen Vision M) that I plugged into my computer speakers today. The way I did it was that I plugged the green audio jack that usually goes into the computer’s sound card into the headphone jack of my MP3 player. It seems to work fine, but I wasn’t sure if this is a safe thing to do or not.

From the Manufacturer
Harman Kardon’s SoundSticks II three-piece speaker system produces high-quality stereo sound for Music, MP3s, movies and gaming experiences. The SoundSticks II system encourages you to step out of the ordinary speaker world and offers sound in an original and unique package. The system, described as curvy, sleek and sexy, delivers sound that is loud and clear. SoundSticks II employs a new computer-optimized multi-band parametric equalization and Harman’s unique “capacitance touch” control buttons on the right satellite allow for direct access to volume control.

Harman Kardon’s 40-watt SoundSticks II three-piece speaker system produces high-quality stereo sound for music, MP3’s, movies and gaming experiences. The mini stereo jack connection allows you to enjoy awesome audio from a variety of devices such as digital music players, computers (all platforms), stereos and portable listening devices. Touch Volume Control – Just a (more…)