While editing a particle hair system (HeadWig) in 2.54.0, Blender suddenly quit when a set of selected keys was expanded using CTRL+NUM+. Upon trying to launch from the most recent autosave (written approx. 5 minutes before the crash), Blender crashes on launch. Trying to open the autosave file from within Blender also crashes.

Appending the HairWig mesh+particle hair system to a new file does not crash. However, once this new file is open, switching to Particle mode and then enabling Point Select Mode crashes Blender.

The autosave file was probably made while in Point Select Mode, which is what likely leads to the crash upon trying to open that file.

Inspecting the particle hair system in the appended file (attached), there are two anomalies compared to the file I was working on when the initial crash occurred:

1) A "stray" parent strand that sticks out to screen left, immediately visible in the UI when opening the attached file. This strand can be edited and/or deleted without problems (although not in Point Select Mode). AFAIK it was not present when the initial crash occurred, though it may have been out of sight in the view I was using at that time. It was certainly not present during earlier parts of the editing session that led to the initial crash.

2) In Tip Select Mode, a "stray" key can be seen in the UI approx halfway along the length of the above "stray" strand. This is apparently the tip key for one of the strands in the edited bundle of strands, but drastically displaced. Selecting it highlights one of the strands in the bundle. It can be selected, but not edited. Trying to Comb it or delete it crashes Blender.

While this may seem like a case of file corruption caused by the crash, recall that the autosave file from which the problematic hair system was appended was saved at least five minutes before the initial crash occurred. Whatever problems the hair system has, occurred during the editing process, not the crash.

A possibly-related anecdotal observation: numerous times while editing an earlier version of this hair system, I observed a number of parent strands that had no keys whatsoever and could not be edited or deleted. This forced me to go back to an earlier save to recover.

Windows Vista Home Premium SP2. 32 bit
AMD Athlon 64X2 5600+, 2.8GHz
3.0Gb RAM
ATI Radeon X700, Catalyst 10.2, 256Mb VRAM
Blender 2.54.0 r31878