Bug: strange behaviour with down-arrow

I'm using 10.1pre4 on 32-bit Windows XP. I'm encountering very strange
behaviour when attempting to move in the document with the down-arrow
key in the WYSIWYG view. This may be triggered by the presence of an SVG
object at the top of the document. I've uploaded a sample document to

http://smithies.org/cpks/test/nl4.html

- when I click on the "TBA" in the rightmost column of the first table,
repeated down-arrows seem to go circularly through the lines of the next
section, and then back again.

If the cursor is located in the paragraph following "Ringing Roadshow",
down-arrow causes the scrollbar to move strangely, the cursor disappears
and it's difficult to recover cursor navigation.

Good luck to the team in tracking this one down!

CPK Smithies