I have Sonar 8.5 and whenever I play a keyboard instrument (like DropZone), if I click a key and hold it, it plays the key but then it starts to make a clicking sound until I release the key. It does this with all of the keyboard instruments I've tried. I'm pretty sure it's not my computer because I've tried it on another computer with the same result. Does anyone know if there's some sort of setting I need to change in SONAR to stop this clicking sound. Thanks!

Welcome to the forum.
What audio interface are you using?
What operating system and is it 32- or 64-bit?
Just tried it on this computer through the stock RealTek sound card. Using DropZone's onscreen keyboard, if I played a note too high on the keyboard, I got a clicking sound as the sample was replaying, and it got faster and louder the higher the note.
No such behavior using SoundCenter's onscreen keyboard.
What happens if you enter a high note of long duration in the MIDI track feeding DZ and play the track? Mine played normally with low notes and clicked with higher notes.
Could be a common occurrence of sample players, depending on the sample. My experience with them is limited.

I figured out that the clicking was coming from the driver. I went to Options>Audio>Advanced and when I clicked on driver mode it gives me four options for drivers: WDM/KS, WASAPI, ASIO, and MME (32-bit); WDM/KS and WASAPI both give the clicking sound, MME fixes the clicking but then session drummer no longer works properly, and when I set it to ASIO, no sound comes out.....do you know what I should do here....is ASIO the correct one and I just need to download something extra? By the way, I have a Dell Inspiron laptop, 64-bit (with 64 bit version of sonar), 8gb memory, 6th generation i5 processor, and Windows 10 64 bit, and I am not using an audio interface currently. On this page       it says if you are using the sound card that came with your computer to choose MME for driver mode, so how would I then get it to play session drummer, it plays the first beat in a drum loop but will not play the rest. Thanks! 
 

Without a dedicated audio interface MME is usually the only driver mode which works. MME should work with everything although it is a high latency solution. How is Session Drummer failing?

It plays only the first beat in a loop but will not play the rest

Usually dropped MIDI notes are the result of too small a "Prepare Using nnn Millisecond Buffers" setting. It has been years since I have used 8.5 and I do not recall where the setting is located that version.

I went into the Audio-general settings and turned buffer size down to 10.0 msec which is the lowest it would go and it seems to have fixed my issues! By the way, do you need an audio interface if you have a piano keyboard that has a USB connection cord  and a USB condenser mic. Would it be wise to buy an ASIO Audio Interface and plug the keyboard in through that and get a non-USB mic to plug into the interface as well? Is 30.0 msec low enough latency to not cause a delay between pressing keys on a MIDI keyboard and hearing them through SONAR? Thanks again for answering my questions I am a new user and trying to learn this stuff

ASIO driver mode is the professional standard for low latency, high performance audio interfaces. That means that all serious interfaces you can buy will come with their own ASIO drivers, which ensure that Sonar can get to the interface without much interference from Windows, resulting in low latency (small delay between pressing a key or singing a note and hearing it back) and stable performance (no clicking etc.).

The main drawback of ASIO in your case, is that audio software can only use one driver at a time. So when you get your interface hooked up, you can't use your USB mic at the same time. For a normal interface this isn't such a problem because it will have inputs and outputs so you can record and play back. A USB mic, not so much. So hopefully it also has a regular XLR connection to hook it up to your interface.

If you're going to buy an interface, think hard about what your plans are - how many simultaneous inputs do you need, what kind of mics do you want to hook up, do you need to expand the number of inputs later on, etc.

Budget wise, set aside at least a 150 bucks for the cheap end of the market that avoids the total crap offerings.

So can you only have your driver mode set to ASIO if you have your interface plugged in? I would probably need an interface with an input for a microphone, one input for my keyboard, and maybe an input for a guitar, but no more than that. Any recommendations for an interface with these requirements that would connect to my laptop via USB? Thanks

http://www.amazon.com/M-Audio-M-Track-Two-Channel-Interface-Plugins/dp/B00NWE79BY/ref=sr_1_3?ie=UTF8&qid=1459377220&sr=8-3&keywords=m-audio Would this interface work for a keyboard and a condenser mic?