Sometimes google docs doesn't display -- tips

When I used firefox for a long time, sometimes when I open the google docs, it doesn't display. But in the mean while, if I use flock (another browser), it works. This means it is not the problem from the server.

Today I met the same problem again, I tried to close all the tabs one by one, until close the whole window, and then open a new firefox. It can open google docs now!