I just tried logging onto another forum that I belong to with Chrome and I'm seeing the same problem when I try to enter my two-word user name on it. It's not an FR-specific problem.
I can post using gmail and text messaging with no problem (as well as with Firefox).
I think that I'll just install an alternate browser. There seems to be quite a few of them available. (I'm not crazy about Chrome anyway.)
It is a memory hog on a lot of devices. Try Dolphin Browser, I’ve had good luck with that in the part.