Microphone keeps cutting out ...

[sabam]

This is a strange phenomenon that no one has been able to explain to me.

While I'm playing an online game and using Ventrillo, my mic (hooked to a mic jack) just keeps cutting out. I use the "Caps Lock" as a hotkey.

If I speak for too long (or sometimes not that long at all) the people who are playing with me tell me they can't hear a darn thing I'm saying.

Is this a problem with my mic jack? Sound card?

I know it's not the microphone itself because I've had three so far and they've all done the same thing. Can anyone help?