Help Disappearing programs

[IanB]

Good afternoon everyone,
Today, various programmes have disappeared from my unrooted DHD (no weird or exotic programmes installed). Missing programmes were Wordpress, Klondike & Evernote. I have had to reinstall them from "Play Store". Any ideas on why? How to avoid this in future? Comments?
Thanks in anticipation,
Have a great day

 

[IanB]

Update,
Today the same thing has happened again. This time the programmes that disappeared were different: Google Goggles, GPS fix, and four others. Any help in preventing this from happening again would be appreciated