I still think it is one of your apps that Google automatically updates. It is not necessarily one you installed recently, just one that updated recently. Try installing a CM with a clean install and do not flash gapps. Try running that for a while. If it still acts up without gapps and it downloading apps, it is a hardware issue.
And there are SD installs by bokbokan for the HD that seems stable, but are not labeled as such.
And I have not heard of an HD with the emmc chip bug.
Sent from my BN NookHD+ using XDA Premium HD app
See my Nook Color Tips Thread here
and my Nook Color EMMC Partition Repair Thread here
and my Nook Color Updated CM SD Installation Instructions here
and my Nook HD/HD+ stock tips thread here
and my Nook HD/HD+ CWM Root Tools thread here
e.mote's Nook HD/HD+ Dummies Guide for installing CM10.1/CM10.2/CM11 here