Sonar X2 rhythmic clicking noises in playback

Hey guys, I need some help because I'm a noob, basically..
 
I've just started using Sonar X2 and learning my way around it. Everything works fine except this one... little...thing that is driving me crazy. If i record audio through the built-in Realtek stereo input and then play it back, I get a rhythmic clicking noise. It's about 100bpm... tick tick tick tick but ONLY when there is sound. In the silence between the recorded notes or sounds, it stops and then starts again with the next sound. You can even see it in the waveform. It's not visible or audible when recording and previewing the wave, only after it's been rendered. It's not the metronome. I've cranked up(and down) ALL the buffers. I've matched all sample rates and bit depths. I turned off as many background programs, anti-virus stuff and windows **** as i possibly could. No internet. Tried different instruments and leads.. all to no avail. It does not do it when I import an audio file and play it. I'm about to try ASIO drivers while waiting on a reply, so if anyone has any clue and could help, would be much appreciated, cheers.

Windows 7 64-bit. 1.8ghz quad core. 4 gig ram. A very clean, healthy system. Sonar X2 64-bit. Everything runs quick and glitch-free. I don't know much about soundcards, but the built-in should be able to record 10 seconds of guitar and play it back at 44.1, 16-bit without any dramas on such a system. I think.... Cheers for your help. 
 
All drivers are updated. Haven't tried ASIO4ALL yet.
 

With the mobo soundchip you very likely can not use ASIO drivers, but ASIO4ALL might work (free download). If you are using MME drivers at the moment, that's the poorest alternative there is. Allthough I don't know if there's MME for 64 bits.

this is likely due to sample rate mismatches in windows audio settings.  close sonar, then in the windows taskbar right-click the speaker and select "playback devices". double-click the speakers that show up in the dialog box and click the advanced tab.  select 16bit 44100hz from the dropdown and hit ok.  then, under sound, click the recording tab and double-click the microphone and select 16bit 44100hz.  realtek only records using a 16bit resolution, though it can play back using 24 bit resolution and both of these sample bit depths and sample rates need to match in windows settings.  i would highly recommend using wasapi mode inside sonar when working with realtek.  let me know if that helps at all. 
 
Best,