In this case, Maya 2015 (Windows) disappeared a few seconds after I clicked the MtoA Loaded check box in the Plug-in Manager. Eventually I tracked it down to this line in my pluginPrefs.mel:
evalDeferred("autoLoadPlugin(\"\", \"PolyTools\", \"PolyTools\")");
Darn you PolyTools, I forgot about you 😉 There’s some kind of conflict between PolyTools (from the Maya BonusTools) and MtoA.
I tracked this down the hard way, by renaming my 2015 MAYA_APP_DIR to 2015-x64.bak and starting over with the default preferences, and then comparing the two.
An easier way (on Windows) would have been to use MTOA_STARTUP_LOG_VERBOSITY along with the -log command-line flag (for example, maya -log %TEMP%\mayastartup.log), which would have given me this:
**** * Arnold 126.96.36.199.wip windows icc-13.1.3 oiio-1.4.14 rlm-11.1.2 2015/01/23 16:50:01 * CRASHED in Tstring::formatToWidth at 00:00:00, pixel (0, 0) * signal caught: error C0000005 -- access violation * * backtrace: * 0 0x0000000045476700 [ai ] AiArray * 1 0x0000000045477eff [ai ] AiArray * 2 0x00000000773cb940 [kernel32 ] UnhandledExceptionFilter * 3 0x00000000774e3398 [ntdll ] MD5Final * 4 0x00000000774685c8 [ntdll ] _C_specific_handler * 5 0x0000000077479d2d [ntdll ] RtlDecodePointer * 6 0x00000000774691cf [ntdll ] RtlUnwindEx * 7 0x00000000774a1248 [ntdll ] KiUserExceptionDispatcher >> 8 0x000007fee46eeb05 [FOUNDATION ] Tstring::formatToWidth * 9 0x000007fee46efff5 [FOUNDATION ] Tstring::set * 10 0x000007febe593e9c [PolyTools ] uninitializePlugin * 11 0x000007febe593feb [PolyTools ] uninitializePlugin ...