The hints above are aimed at decreasing latency in processing what you are recording, so that what you are recording is processed and comes back to your headphones as quickly as possible and to your ears is timed with with the other tracks you are playing. If there is a lot of latency, then you will hear all the tracks but what you are singing is delayed in coming back to your ears. This shouldn't really delay the recorded signal, but with much latency it's nearly impossible to stay on with the other tracks -- so you may just be singing behind the other tracks due to latency. As Jim suggested, decreasing the ASIO buffer setting will decrease latency, at the price of also decreasing stability (ie, more likely to get glitches in processing if you have a lot of CPU heavy processes.)
Some effects really impact latency -- I had this same issue with Sonitus reverb, which is a convolution reverb, until I learned that needed to be turned off for tracking; I use Guitar Rig and run into latency a lot with that too, even when I have the buffer size at a minimum. So now when I am recording anything, I turn off all instances of Guitar Rig, Sonitus reverb, and other processing-heavy effects; I leave Guitar Rig on on the track I'm recording. I leave the effects turned on only where I need them to get the feel needed to record it. If you have a lot of synth's running that may do it too.
If you need more of the "feel" of the effects, you can always bounce the track, or freeze the synth -- that will hold it as an audio track with the effects as part of the audio, so it's not taking any processing power.
On the other hand, if your latency is minimized and your monitor headphones are synched with the tracks and you're playing and singing along in time with the already-recorded tracks -- but it's just recording a delayed signal...I'm not sure what to tell ya. I've had a few instances of that in the past - I think before X2 came out -- but that was a pretty significant delay, not a small one. And taking it out of record mode before playing back would fix that, as I recall.