Over Modulation during Recording

On playing a record the waveform appearing over modulates especially when there is a high volume from the track. How do I reduce this over modulation? The gain on the turntable is at its minimum position

You may need to turn down the computer system recording level.
On Windows Vista / Windows 7, the quickest way to access the mixer is to right-click over the speaker icon in the System Tray > Recording Devices