Continuing from the old board: basically I have a laptop where installing the VS2008 runtime wasn't enough to clear the error. It was an odd one: it happened under XP (downgraded from Vista) it happened under wine on Linux, and it happened under XP running on virtualbox. All of these work fine on my desktop machine, so I should be able to get one of them running on the laptop.
Anyway - last night I installed VS C++ express on my laptop and, not surprisingly, WM now works, at least under XP. So, there's something else in the VS install that's needed and that's not covered by the runtime.
Not much help, but it gets us a little further forward.