Pages freezes when I save a doc after changes. I have to force closure during a reboot.

Machine used:

Macbook Air, Memory: 4 GB 1600 MHz DDR3, Processor: 1.4 GHz Intel Core i5

OSX Yosemite version 10.10.3

Product Pages 5.5.3 (2152)

Pages goes into freeze when I close a document. The only way to resolve this is to force closure by restarting the Macbook, which then asks if I want to force close Pages.