Replying to a message not working

[frogsandfish4u]

When replying to a message I received as I've done for the last 16 years, I am able to type one character then the line disappears. I place the line again, type another character, and so on. This is the first time I've seen this type of reply page and so far.....

I don't want to have to type the message elsewhere and then cut and paste.

Thanks for your assistance.