The last couple weeks I've been seeing the infamous "Unable to install" error message pop up off and on. Yes, I have done some manual updates for my apps, but they all updated ok and all are working fine. Except freaking Twitter. The last two updates are almost immediately replaced by the Nook's system version and as a result, it's not usable (not that I use it anyway). This message popped up two days in row now after leaving my nook on the charger overnight. This is not only worrisome for me since I saw on here somewhere that someone had apps removed and were unable to reinstall them (so far not the case with me), but annoying as well since it NEVER says which app it is!! I am beginning to believe this may be caused by damned Twitter REFUSING to let me update since that is the ONLY app of mine that can't be updated. I downloaded Greenify to try to see if that would help stop the constant antivirus notifications that were indicating that Twitter was rolled back to the system version. But if this happens again, I will have to do some serious tablet research since I have no intention of ever buying one from B&N again nor will I let them ship me a replacement regardless of the extended warranty.