Have you made any changes recently (and I mean "any")? I know this is a dumb question, but any information might help in spotting a solution. For example, I once made People crash reliably by using Titanium Backup to "freeze" Flickr (not a problem as I was pretty much expecting it, but it illustrates how different applications and services can be linked).
My suspicion is that whatever's causing people to freeze may be the problem - all 3 of these apps will depend on the contacts database, and may have some software dependencies. If not an app modification, maybe some corrupt data could do this. Do you have a recent backup you could restore from?