Thanks Phil and MGW! To answer your questions:
It gets stuck on random presets, this morning it was a stock one that came w/ the unit... yesterday it was one I purchased in the Line6 marketplace.
Yes, I have done a factory reset since the update, then I restored my presets from a backup.
Helix went through a lengthy preset 'rebuilding' process upon restart. I thought that might fix things, but it actually made freezing worse. Much worse.
Maybe I just need to keep doing factory resets and installing old presets one at a time???? (ugh)
Maybe I fried the motherboard or something????
I'm all ears for suggestions... I'm on the verge of sending it in for some Line6 workbench time if necessary.