From what I understand that message can be a little generic.
I would start by suggesting clearing out your browser cache as that has caused some issues in the past.
Then try with an INCOGNITO window with addons disabled to make sure its not a browser add on that is acting up.
It may also be worth turning off any third part security simply to test and using the steps above too.
There are some quite important facts missing from your post so I would recommend reading a few of the posts that are stuck to the top of this section.
Type of internet connection and speed of the same can also play into bad connections where pages time out.