How to fix "Unfortunately the process android.process.acore has stopped"?

[Android Central Question]

I had facebook and yahoo mail. Cleared contacts and deleted facebook and yahoo and it was fixed. I reinstalled facebook and it started again so i deleted it and it stopped. Then today I installed yahoo mail again, thinking facebook had been the problem, but it started again. Now, I deleted yahoo again too, and cleared my contacts but I'm STILL getting the error! Please help anyone!