I was recording with TTS-1 on a track using a organ preset. Worked fine, closed x2, opened the next day to try and re-record and now when I press the keyboard, there is a slight delay in hearing the note. I don't think I've changed anything from the previous recording. Usually something overlooked and simple but stumped again...

preferences/audio/driver settings,  check your buffer size !!!

As Chregg said, delay like this it could be buffer size
 
Alternatively, If you press "E" on your qwerty keyboard, does it go away?

Two good suggestions.
 
To elaborate a bit on the 'E' on your keyboard idea - the letter 'E' is a hot key that tells Sonar to bypass all effects.  Hitting it again will toggle the effects back on.
 
It is a quick way to determine if one or more effects are causing this delay for your project.
 
Bob Bone
 

Thanks for the help. I did hit the "E" to bybass the effects and sure enough I was able to get the keyboard to respond as I'd like it to. I'll have to record that keyboard track without any hearing any effects on any of the other tracks also, but no problem. Easy enough to tweak later. Again thanks for the tips...

dotonemanband
Thanks for the help. I did hit the "E" to bybass the effects and sure enough I was able to get the keyboard to respond as I'd like it to. I'll have to record that keyboard track without any hearing any effects on any of the other tracks also, but no problem. Easy enough to tweak later. Again thanks for the tips...

Yes, I'm sorry not to have gone into any more detail, but just asking you to try this would rule out the possibility.
 
Certain plug ins cause latency, either by being "look ahead",  or CPU intensive, like a convolution reverb.
 
Typical culprits in Sonar are PC Concrete Limiter, Perfect Space reverb, LP-64 EQ LP-64 Multiband compressor, Boost 11, TS-64 Transient Shaper, R-Mix, etc.
 
If you have one of those, disable it, and the latency should disappear. You can then re-insert it when you have finished tracking.  You can still have the other effects/processors in your project.

Yay!  A success story.
 
Bob Bone
 

I was in fact using the LP 64EQ effect. Had no idea that was the culprit...now I know...thanks for info jb101....now it makes sense...again, the forums have been very helpful....

Usually effects like LP-64 are reserved for the mixing process. The Prochannel QuadCurve or Sonitus EQ will allow you to EQ without adding latency. All of the Cakewalk effects with look-ahead buffers are documented as such in their help files and have some indication of the latency that they add.

dotonemanband
I was in fact using the LP 64EQ effect. Had no idea that was the culprit...now I know...thanks for info jb101....now it makes sense...again, the forums have been very helpful....

I wish there was a sticky thread posted at the top of the forum that listed such effects that can produce these kinds of latency issues.  I believe it would greatly cut down on the number of threads posted on this very issue, as it does pop up at least a couple of times a week, if not more.
 
Bob Bone