B4 distortion - not the good kind

I'm trying to run B4II on a laptop through an E-MU 0202 audio interface controlling it with an M-Audio Oxygen 61.
B4II runs fine on the laptop without the audio interface – i.e. using the computer's soundcard. Buffer size is around 20-25ms.
However whenever I run it through the audio interface I can hear it but it starts to distort after about five minutes no matter what I do to the buffer size.
I've made a note below of the settings I'm using in the audio/midi settings. Some of these settings I chose while some - such as inputs - were just all there was. I don't know if it would be possible to take a look to see if I am making a fundamental mistake. As I said the software runs no problem without the audio interface.
I'm listening via headphones plugged into the interface's stereo output.
Any help greatly appreciated.

Soundcard

Interface: ASIO
Sample rate: 44100
Output device: ASIO E-MU0202/USB

Asio configuration:

Preferences:
Buffer size: 20ms (tried every setting)
Bit depth: 24-bit

Routing:

Inputs:
Left input: Analog in A

Outputs:
Master left: Analog out
Master right: Analog out

Midi:

Input interface:
USB Oxygen 61 in – on

Output interface:
Microsoft Wavetable Synth – off
USB Oxygen 61 in – off

Any help greatly appreciated.

 

The answer is download the latest E-MU drivers for the hardware and remove any anti-virus programs.