Eh. :debug_log:
EDIT:
Please generate & post an fs2_open.log file. Instructions on how to do so can be found in this post.
The tl;dr is, select the appropriate debug build in the launcher, run it until the problem (Theseus exploding) occurs, quit, find the fs2_open.log (usually in the \data\ subfolder of the game), and post that here.
If you can't find the log file after generating it, search for it using Everything.
Ran the FreeSpace 2 Open Build 1 Diaspora Debug, it gave me this warning while loading the mission:
Submodel <Seata> in model <Col_Viper_Mk7.pof> has a radius <= 0.1f
ntdll.dll! NtWaitForSingleObject + 21 bytes
kernel32.dll! WaitForSingleObjectEx + 67 bytes
kernel32.dll! WaitForSingleObject + 18 bytes
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
fs2_open_Diaspora_R1_Debug.exe! <no symbol>
kernel32.dll! BaseThreadInitThunk + 18 bytes
ntdll.dll! RtlInitializeExceptionChain + 99 bytes
ntdll.dll! RtlInitializeExceptionChain + 54 bytes
I clicked no to continue loading the mission, but the game then froze while loading, had to kill it. I've included the FS2 Log it generated, hope this helps.
[attachment DELETED!! by Strong Bad]