I've been using PAF 4 for about a year now. I'm very happy with it except for its habit of losing my sources. Out of a list of about 50 sources, about half of them inexplicably vanished about 4 months ago. The citations for individuals remained (i.e. Citation 1 or 2 or whatever), but the citation screen was blank. Figuring I must have screwed up somewhere, I painstakingly re-entered them all, only to have the exact same thing happen again yesterday. Has anyone else had this problem? Is it something I'm doing?