One: why might Ubuntu have refused to boot? Refused to do nuthin after
the grub menu -- zilch, blank screen and no disk activity, until I
recovered which included running the requisite disk test.

Two: I've heard it said it's better not to use Linux to write to an
NTFS partition, but sometimes I need to do so. I didn't install any
special utilities. Aside from being careful with file names is there
anything else I need to watch out for? Do I need a utility?