If you have a trial version of Office 2003, then maybe the trial
period has expired? Some trial versions cannot be converted to
perpetual versions from the Activate Product dialog box... you
can always purchase a full version of Office 2003 (or an upgrade
version if you own a qualifying product) from your favorite local
or online retailer.

Fenix wrote:
I'm having the same problems with all new and exisiting documents
"modification not allowed because the document is locked"
I've clicked on Help/Activate product but nothing happens.
What can I do?