I agree about the file permissions. You may try Run-As in Windows to get around the permissions issue, but I’m more concerned about your DVD being required. From your description it sounds like not all components were installed locally. If you run through the setup screen a second time, confirm that everything is marked to be installed to your local hard drive destination.
You might have to setup file permissions, when you installed Word did you select to install it for all users or explicitly for that account alone, because aside a complex issue of trying to give access rights you probably may need to reinstall it from the user account (and it’ll ask for permission at admin level when required).
if its working fine under admin account then there must be some permission issues otherwise DVD issue arise only if you failed to install required component that need optical media to run.