When raising to 3D, AutoCAD crashes with no error, no warning, it just closes.

You can test this by closing all open drawings then starting a new drawing using the Hydratec template, "Hydracad Imperial Default".

Draw one pipe 10' long (LN command). 

Place a length & 2" diameter on it (SZP command)

Place a 10' AFF elevation mark on it (AFF command)

Start the process of raising to 3D (S3D command).  It will then crash out without warning around step 2 (something about sprinkler heads).