Mission Error

Hey all,
I've been working on a fairly ambitious mission and have hit a snag.
Since my last round of changes my game crashes upon launch. Sometimes I am able to get to the first triggered enemy event but the error is the same;

Assertion Failed
OBJPlayer.cpp
Line 162
Expression: pos.x > -SPACE_SIZE_W

Followed by:
Problem signature:
Problem Event Name: APPCRASH
Application Name: Artemis.exe
Application Version: 0.0.0.0
Application Timestamp: 5130c323
Fault Module Name: Artemis.exe
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 5130c323
Exception Code: 80000003
Exception Offset: 000b98f9
OS Version: 6.2.9200.2.0.0.768.101
Locale ID: 4105
Additional Information 1: 5861
Additional Information 2: 5861822e1919d7c014bbb064c64908b2
Additional Information 3: dac6
Additional Information 4: dac6c2650fa14dd558bd9f448e23afd1

I had a similar issue previously but it was caused by setting a coordinate outside of "regular space". I've reviewed my code and don't see any such errors.
I also found other forum posts with a similar SPACE_SIZE_W error caused when multiple objects have the same coordinates but I cannot find any instances of this either.

Thoughts?

I would rather not post the entire xml but can send it directly if anyone wants to have a look.

T