ok two updates:
first - skype wasn't causing my contacts to FC. a bit of searching revealed that it was because i'd disabled the yahoo apk. wtf does that have to do with my contacts? i don't have any accounts with yahoo, and never have, so what gives?
second - the phone has been really flaky lately - randomly i open an app (any app) and within about 3 seconds, it drops back to the home screen. no FC message or anything - it just quits. after it does that, the only way i can use that app again is to reboot. sometimes other apps will continue to work after one has started flaking, but not always. the most common failures are scramble/words with friends, dolphin, ES File explorer, and draw something. that's just because they're the ones i use the most. once one has flaked like that, others are much more likely to also flake - radio thermostat, gtalk, gmaps, even market (play), and so i just have to reboot.
the way i did my manual debloat was not using TiBu. I just went into system and renamed the apks i didn't want to .old so they couldn't load. that worked great on my D2, and left them there in case i had to put them back (good thing, since it turned out yahoo has its grubby little fingers in my contacts for some unknown reason). so since it's been so flaky, i went back and took off the .old for everything, and left droidwall disabled, so the phone is basically back to stock, but it's still rooted. i think my hosts file still has a bunch of ad-blocking stuff in it, but i wouldn't expect it to cause this... but then i didn't expect a stupid YAHOO apk to break contacts, either... i'm just about to unroot it, reset, and send it back. so far i'm unimpressed by the d4 - especially the battery. If only i hadn't lost my temper and smashed my d2, i could go back to it... it needs a whole new upper half though...