If I try to open a project that contains sysex banks set to MIDI outputs that no longer exist, Sonar Platinum crashes.
 
Sonar X3 will load the project allowing me to delete the banks and re-save, but I get the usual warning on startup that it was saved using a later version and some features may be lost.
 

What is your Playback, "prepare using" setting in Preferences | MIDI | Playback and Recording?  For some reason, if I load a MIDI only project, Sonar Platinum will crash if I set a value higher than 290.  This may be a machine quirk that only I am experiencing.  Most of my MIDI projects are heavy with Sysex at the start and throughout the sequence.

Maybe try values between 250 and 290 for the above, see how that goes.

It's set to the default of 250.
 
I'm pretty sure this issue is to do with the MIDI device number in the SYSEX bank being larger than the number of devices available. It looks like this is fine for MIDI tracks - i.e. SPLAT just ignores the fact that device doesn't exist, but obviously not for SYSEX banks.
 
The SYSEX banks are not sent to auto-play on project startup (they are my stock custom sounds for a Roland CM64 which has no permanent memory, plus effect routing for my Yamaha MU10 which I use to effect my Yamaha TX81Z and Kawai K1). Sonar X3 correctly prompts me whether I want to send on startup, whereas SPLAT just hangs.
 
I've spent a good few weeks sampling all the sounds I use in my hardware synths, so I can retire them - well at least semi-retire them... I'm not quite at the point where I feel I can let them go! But for day to day use, I'm going to a VSTi only setup.
 
Now what I'm doing is going through all my old projects and getting them to use my samples instead of the original hardware synths.
 
To be honest, it's not a huge issue for me as I've got a workaround. Loading the project up in X3 allows me to get most of the way, then I can take over with SPLAT.
 
It is however a bug, so I've posted it up so Meng/Noel are aware of it.
 
M.