LibreOffice going banannas

I'm experiencing a horrifying bug in LibreOffice 4.2.7.2 on Trisquel 7.

It has two parts. First, when deleting text using the backspace key, it only deletes slowly, one letter at a time (even when I press the key much more frequently or hold it down). But then, once I've released the backspace key or stopped pressing it, it keeps deleting for a long time afterward, deleting lots of stuff I didn't intend to. When I say a long time, I mean a long time. Like, I'd estimate at the worst 10 seconds or more.

This behavior survives restarting LibreOffice and rebooting the system. Nothing I tried stopped it from behaving this way.

Then, it progressed to part two of the bug: every key behaves as the backspace key. Arrow keys, letters, doesn't matter. It treats all of them as if they were the backspace key.

It goes without saying that it's difficult to get work done this way...

Any ideas greatly appreciated.

Boaz