Try 512 samples.

Also, turn off windows sounds by going to your computers control panel and selecting SOUNDS AND AUDIO DEVICES - SOUNDS and under SOUND SCHEMES select NO SOUNDS. It's a good idea to disable any screen saver you have running and to edit the taskbar so as not to display the clock. All these things can affect how audio runs.

Final thing - click the MIDI button to go to MIDI DRIVERS and de-select all the output drivers. If you're using DXi or VSTi sounds you don't need output drivers and they can cause problems with the ASIO drivers.
Good luck. Keep us informed.

ROG.