Snap/crack sound when clicking around Windows.

Hi, I'm currently using 2 KRK RP 5 monitor speakers connected via RCA's from my creative labs xtreme audio pci-express sound card. My problem is, when clicking around windows, it may make a pop/crackly noise when the "click" effects come through. Music, movies, games play flawlessly with no artifact. My sample rate is at the default 16bit, 44khz, my gain on each speaker is -10dB, and my system volume is 6%. I'm using windows 7 32bit RC 7100, latest drivers for everything. A change in OS hasn't helped either. Any ideas? Do you think using XLR or 1/4" inputs would help?