enabe/disable autocomplete through C++

I am trying to enable/Disable auto complete of web address in IE7 through C++
executable. I am modifying the registry entry with an IE window opened. The
registry entry modified is as shown below
[HKEY_CURRENT_USER\Software\Microsoft\Windows\Curre ntVersion\Explorer\AutoComplete]
"AutoSuggest"="no"

The current IE window is not getting effected because of the change. If i
see the autocomplete settings of the current opened window (tools->internet
options->contents->auto complete settings->) web address is unchecked. But
the change is effected in new instacnes of IE. What should i do further to
disable autosuggest in the current opened IE window programmatically?

I am using Windowx xp sp3.