Problem: I have Ubuntu 14.04 with Xubuntu desktop and my Indicator plugin kept crashing. Here's how I fixed it!
Solution:
a. Add Indicator plugin to your panel.
b. Once Indicator Plugin is added (and before it crashes ;-)), right click on it -> Properties -> Check the Hidden checkbox for Application Menus (Global Menu) (as shown in the image below).
c. Restart the panel with xfce4-panel -r
Reference:
AskUbuntu: Indicator Plugin keeps crashing