MS Word freezing up, partially (just parts of the interface) or completely

Macbook Details:

OS X Yosemite

Version 10.10.2

MacBook Pro (15-inch, Late 2011)

Processor 2.2 GHz Intel Core i7

Memory 4 GB 1333 MHz DDR3

Microsoft Word for Mac 2011

Version 14.4.7 (141117)

Latest Installed Update: 14.4.7

MS Word has really been acting up lately. I am not able to switch freely between the tabs anymore (except on a good day, maybe once a month). I can only use the Home and Review tabs. Sometimes, for example, if the Layout tab opens, then I will lose the ability to go back to the Home tab, so I'll have to close the application and start over to continue using the basic formatting options on the Home tab.

I know there are ways to use all Word functions by using the Menu Bar, but it's irritating and absolutely ridiculous that my interface is so messed up. The program is generally weak and prone to freezing if I open up more than one window or try to work with a document 5+ pages in length.

Any suggestions on what I can do?