Microsoft Office 2003 document (Excel and Word), intermitently, takes 30 seconds to load

Like Pynner suggested, I bet it has something to do with the time-out to access network-shared folders, which are for some reasons unavailable.

Try to disable all network interfaces and then try to reproduce the problem again. If I am right, there will be no delay this time, as all network related operations will fail immediately.

This sounds very much like it is scanning for a missing network resource, such as an intermittent Network Share that happens to be in the search path, or a security access authorization lookup, etc. (there are many possibilities).

Here is a blog article by the creator of both Process Explorer and Process Monitor (Mark Russinovich) explaining how he diagnosed a very similar problem: http://blogs.technet.com/b/markrussinovich/archive/2005/08/28/the-case-of-the-intermittent-and-annoying-explorer-hangs.aspx.

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I have to point out that I have been afflicted with the notorious "30-second Explorer Hang" more than once, and almost every single time it turned out to be some obscure UNC reference to a sever that either no longer existed or that was not accessible at that time. I'd suggest that you try search your registry for "\" and make sure that all of the occurrences you find are to servers that actually exist.

Don't forget a shared Printer can easily cause the exact same issue. Happened to me on my MS Word 2003 whenever that shared network printer was turned off.