I have a project recorded @ 44.1K with several tracks and all sounds fines. I recorded some guitar overdubs and somehow the project sample rate got set to 48K and my audio interfaces sample rate was left at 44.1K. Now all of my guitar overdubs gradually get further and further out of time when I play them back. Is there anyway to save those overdubs? Re-recording is an option but I'd have to call the guitar player back to do them.
 
Thanks
Pete

How can this happen ???
First make a backup of the project.
I would convert all wav-files from 48 to 44kHz outside SONAR with any audio tool. Just go into your audiofolder and convert this files. Then start SONAR with this project - it must show @44kHz because all files are at 44kHz. I have done this already, it works.  (Of course you can also convert all files from 44 to 48kHz)
 

+1. There are free sample rate converters for files all over the place.

Thanks guys. I will try this later today and let you know how I make out.
 
So, I think I've figured out how I got into this position:
 
 
Project "A" (10 tracks) was recorded with my audio interface set at 44.1K.
 
At a later date Project "B" (multiple tracks) was recorded with the audio interface set at 48K (not sure why).
 
The next time I opened Project "A" audio interface is still set to 48K and I record my guitar tracks and I have the problem I describe in the original post. That's the only scenario I can come up with that would have let me mix sample rates within a project.
 
Thanks
Pete
 

I am completely baffled. I opened the audio files for the guitar tracks that were suffering lag in Audacity and it says they are 44.1K. I also opened all of the other audio files for the project one at a time in Audacity and they all are 44.1K too so I guess I don't have a sample rate problem. Arg!
 
The lagging guitar tracks were recorded in loop mode so I got multiple takes which get further and further out of sync
with each new take.
 
 

It could be the file headers show 44.1k but the audio is actually recorded at 48k. To test this make a copy of one of the wav files and use SoX to fix the file header using the command
sox -r 48k infile.wav outfile.wav

What you are describing is not sample rate but what happens when a driver does not report it's latency to Sonar and timing will go off. You can test this with a lop back test. 
It does not normally occur when using good ASIO drivers. 
 
So you only need to nudge the tracks to where they belong. Sample rate missmatch would also have them playing out of key. 
 
You should really do a loop back test and check your offset timing. 

Let's assume there are no tempo changes. Let's assume the loop points made an exact number of measures.
 
The loop recording bug (error in the length of each pass) was finally fixed in X1d (which X1 is the OP using?). Combining loop recording with punch-in recording still didn't work quite right.
 
One possible workaround is to find the file that received all the takes (there is just one holding all the passes recorded with a single press of the record button). Put that file on the timeline to see if the takes now line up at measure boundaries.

Cactus Music: I am using X1d and ASIO driver mode with my Roland Quad Capture
bvideo: No tempo changes but.. the loop points were not made at exact measures and I'm sure that I was using punch-in record and I remember thinking that those punch points didn't exactly match up with loop points.
 
I'll try nudging around the audio file.

I was able to move the takes out to separate track and nudge them around to put back in time. Thanks everyone!