I've been working on a project for a few days now and everything has been fine until tonight. I decided to re-record one track and now there's a latency problem. I can close this project, open a new one and record fine. For some reason there's lag when trying to add more tracks to this one project. I've tried adjusting the latency within sonar and presonus, but nothing works.
 
Anyone have any clues what could be the issue here?

I'm no expert. But, the first suspect is usually your effects & synths. Some of them can cause a good deal of latency. Press E on your computer keyboard. This will bypass all effects. See if anything happens (for the good). I've learned this amount of troubleshooting from the experts here ;)

Thanks, FullBug. I have tried that and it didn't work. :)

It seems to be getting worse. Now there's a track playing that I deleted the other day. If I mute my drum track it mutes the deleted track, but the drums keep playing. Freaking odd stuff here. I'm thinking it would be easier to just start over. I would hate that though!

Maybe saving your project as a new file? What synths are you running?

This is the second time I read about a deleted track continuing to play back in X-version. I don't remember if they found a fix to the previous one a few months ago.

I have sometimes (PE 8.5 and 6) experienced sudden added latency. The cure for me has been toggling audio engine on and off.

The only thing I had running was amplitube, prochannel and an EQ. I just created a new project and imported the recordings from the other one. Everything seems ok now, but no clue what happened to it. Was working perfectly then suddenly FUBAR... I noticed some funkiness with tracks on that one the other day now that I think about it.

i was going to suggest what you did. sometimes cwp files just get trashed. 

This is just a complete shot in the dark but do you have a "DELAY" bus?

I thought I had exactly the same symptoms last week when I added some soft synths to a project (increased latency for no apparent reason)

What had actually happened was SONAR had set my DELAY bus as the default BUS (no idea why and it has changed this a few times) so when I tried to play something I was hearing the 100% WET signal only - which meant it didn't play immediately and sounded like "lag" / latency

You haven't mentioned delay so it is unlikely here but thought I would give a heads up in case

I have noticed strange things happening with Sonar and Studio One when using Amp Sims.
The CPU spikes and drags the whole production down.
Killing the Amp Sim or bouncing to track seems to calm things down a bit. Not sure if this is what is happening to you or not, but it sure is a work flow killer, if you were not ready to print to track quite yet.

I didn't have any kind of bus, except the master. I removed all sims, prochannel and EQ. The "phantom" track and the lag was still there though.

Redoing the project wasn't that painful really, I wasn't totally thrilled with a couple of things anyway. But, I would still love to figure out how that one track reappeared embedded in my drum track.