QDirModel::setLazyChildCount not working

Hi,
I have a dialog with a lot of edit fields which use the QCompleter with a QDirModel to autocomplete filenames, just like the Completer Example.
The problem is that the QDirModel accesses my floppy drive to see if it has any folders which makes the application freeze for a while.
According to the documentation QDirModel::setLazyChildCount(true) should take care of this, but that isn't the case. Should I file a bug report for this?
Does anyone have a workaround which doesn't include filtering for the string "A:\"?

I'm using Qt 4.2.2 for windows with MSVC2005.

The docs don't state it'll not access the drive. QDirModel has to check if the path is a directory or not, it just doesn't look inside it to check if it has children.