Can create new document, but can't enter text!

Can create new document, but can't enter text!

The subject says it all: today when I logged into Zoho Docs I found that I could successfully create a new document, but I can't enter any text in it. My cursor doesn't appear in the document and typing doesn't appear, and I can't paste anything. I don't know what's going on - I use Zoho docs regularly and this has never happened before. Does anyone have any suggestions??

Thanks!