Word won't open after service pack 3

My computer automatically installed sp3 and since then, when I try to open a word document, I get the error:
'The command cannot be performed because a dialog box is open'.
When I close this box I have a box that says 'Windows installer preparing to install' which then just closes.
I have Office 2003.
The Microsoft website suggested deleting templates in the Word startup folder, but I had none.
Another site suggested Norton Antivirus to be the cause, but I run Avast.
I have tried to system restore to before sp3 but it won't do it.
Does anyone please have any suggestions?

 

Can you uninstall and reinstall Office? That would be the easy fix. When you refer to service pack 3, are you talking about Windows XP Service Pack 3? or Office 2003 Service Pack 3? There's a difference. If it's the Windows SP3, try uninstalling it by following the steps in this article. If you have your Windows XP install disc and product key, you can perform a safe re-install which will revert your Windows back to the service pack on the CD. Use this guide to learn how to do the repair install. When done properly, there's very little chance of any data loss; only if the user profiles are messed will there be any problems, but you won't loose anything, but all your desktop icons will disappear, but that's very rare.
Good luck!

 

dlb,
Thanks for the reply.
It was Windows xp sp3. I removed the sp3 update but still have the same problem.
I cannot find my Windows XP install disc.