hashcat stops after about 37 minutes

[patpro]

Generally I don't use betas, but I've re-downloaded hashcat and checked its checksum:

$ sha256sum hashcat-3.6.0/hashcat64.bin
4ee2a4d04fa06faa86659f0c1a79264123cead264528eae84b79a439414faf6e hashcat-3.6.0/hashcat64.bin

same value for the one I'm currently using and the one I've just downloaded (https://hashcat.net/files/hashcat-3.6.0.7z)