OK, with a new install of ArcaOS 5.0.2.3 and adding netlabs-exp to ANPM and updating everything and a new profile, I can reproduce these problems, eg the add-ons page spiked one core and never finished loading.
Tomorrow I'll spend some time comparing the 2 systems. My guess it is one of the DLLs in exp, which I don't have enabled on my main (this) install.