As usual, I’m late to the party, but @Amber has made all good suggestions. And I’d second trying out chrome as an alternative. I’ll need to confirm it, but I’ve heard of Firefox having a few issues here and there lately. And Safari doesn’t tend to work with anything that requires flash (most things on the internet).
If that doesn’t work, you can try saving the document as an older version of word (or as a compatible file...that option is under the “save as” drop down).
Hopefully, one of these options works.
If not, I’d do as @AgentPete suggests and answer the above questions so we can narrow down what might be wrong.