Windows XP Pro - Run Menu autocomplete problem after SP3 install

I started installing Windows XP Pro SP3 this morning via WSUS. The first machines seemed to patch OK apart from one problem.

The autocomplete and autosuggest on the Run Menu and Explorer address bar have stopped working.

The urls in the typed history are still there if the drop-down is clicked but they don't appear as you type. File paths are not prompted either.

The autocomplete works fine in IE 7 and in file dialogs.

The suggestions I've found so far all seem in order:

• The options to use autocomplete are checked in Internet Options | Content | AutoComplete | Settings


• 'Use inline AutoComplete' is checked in Internet Options | Advanced | Browsing


• TweakUI has 'Enable AutoComplete' checked in the Common Dialogs options.

Registry:

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\AutoComplete]
"Append Completion"="yes"
"Use AutoComplete"="yes"
"AutoSuggest"="yes"
"AutoComplete In File Dialog"=dword:00000001

What can be causing this?

UPDATE: Autocomplete has started working again on the affected machines, so it must have been fixed by patches applied in the last couple of weeks.

Has anyone else experienced this?