Sonar x2 producer, Saving Issue

Hi,
Having problems saving In sonar.
I open an old project that I have been working on, then without changing anything, go to save as. Save it under a different name but in the same folder. After closing sonar, opening the new file makes Sonar crash. 
This happens every time, even if I open in in previous versions of sonar. eg 7 producer.
No settings, updates or hardware have been changed.
 
However if i start a new project and save it its fine.
 
Does anyone have any Ideas?
 
Thanks.

Hi CJ thanks for the reply.
 
The track consists of.
One vst, superior drummer 2.0. 
All fx plugins used were cakewalk's own and supplied with X2.
And about 80mb of 24 bit audio.
 
I use a Roland/Edirol UA-25EX interface with up to date drivers.
Windows 7 32bit, 4gb RAM, 2.53GHz dual core. Hp pavillion Laptop.
Never been on the Internet, never install any other software, its only ever done music creation and never had any problems with it before.
 
I can restore the project to an earlier version but the problem of saving still exists.
I have also use the file restore (holding down shift when opening the file) but this doesn't seem to make much difference. Even if I open the project without any plugins it still crashes.
 
I had also started a new file to copy all of the audio and midi data, plugin settings, etc.
Took forever and still once saved and the programme closed it won't open again.
 
Made me think it might be corrupt audio. But I don't think this is the case as I can still access 100% of the data on the restored file.
 
Very odd.