Andy - thanks for your reply; I'll give that a shot and see what happens.

My client informed me today she'll be upgrading her hardware very soon anyway, so a solution to this problem is not as urgent as it once was.  She seems to think that it only affects IE v6.0.2800.1106.

As such, I won't be able to relay any more feedback from her as to whether example pages work; things to try etc, so I won't be able to post any leads.