Wierd Problem of slowed down tracks [Solved Sort of]

On opening some all-audio songs (about 2 years old but regularly opened and tweaked) in Sonar X3e -after applying the patch - I noticed that they were playing slightly slower than normal in other words the pitch was a semi-tone down. This is the first time it happened (after the 3e upgrade - it didn't happen before) but it also happened today in when I tried the said files in Sonar X2b.
 
They were recorded at 24/48 when my system is set up for 24/44.1, but the audio device changes over perfectly.... I think. I have a Focusrite LS56, in Asio mode with a buffer size of 512 (don't do much low latency recording) and in Sonar the I/O are 256/256
 
All other songs, with a mixture of audio and midi, play at normal speed and normal pitch.
 
I'm up to date with all drivers etc and plug-ins were re-scanned etc
 
Of course I would love it to be user-error, but I can't think of anything I've changed apart from upgrading. But then apart from these 9 tracks, everything else is normal.
 
Anyone one else come across this phenomenon and if so how to cure it ?
 
Edit : I have one of the songs bounced as a pre-mix, it plays perfectly in WMP, correct pitch, correct spêed. In Sonar 3e, as above.
 
Yours most baffled,
Jerry

Ok so i cold rebooted. In Sonar's preference changed the setting to 48000, tried to play a song and zilch. Changed back to 44100 then cold rebooted and everything is hunky dory.

Bizarre.........

I am no expert at this stuff but I would try setting Sonar to 48k and see if it makes a difference

I second that. From 48Kz to 44.1Khz would sound exactly like what's described. A slight, but noticeable slowdown when the project is set to 44.1Khz after being recorded at 48Khz.