slow address lookup and saving files outlook 2000

[superture]

Hello

Sometimes outlook is very slow on looking up addresses. I write some
letters and then hit ctrl + k for lookup. That sometimes takes 30-45
seconds. Same happens sometimes with saving files from e-mails. It
takes 30-45 seconds before the drop down menu in the save window is
chooseable.

We have a 2003 AD with Exchange 2000 Enterpris.

Regards

Magnus