HELP FILE

Q My computer couldn't download one of Microsoft's critical updates. I've tried to get this to work four times, but I keep getting the same error message: "Update was unable to be successfully installed."

AMost of the time, Microsoft's system-update routines work just fine, but problems like this one do seem to crop up on random occasions. When Windows Update acts up like this, though, you can still download the file off Microsoft's site if you're willing to take a slight detour through Microsoft.com.

Should you get one of those unable-to-install errors, jot down the alphanumeric designation of the update (in this reader's case, "KB913446"). Then visit http://www.microsoft.com/downloads and run an "All Downloads" search for that sequence of letters and numbers.

You should get a list of several versions for the various editions of Windows Microsoft has shipped; make sure you choose the right one! In most cases, that will be the garden-variety Windows XP download, but if you're running an older or newer release (for example, the 64-bit edition of XP), you'll need to find the right flavor of download on that list.

When I shop online, I sometimes get a message saying that a "500 Internal Server Error" has occurred. Do you know what this means and how to fix it?

It basically means that there's a problem at the Web site, nothing more, nothing less. There's nothing you can do but wait for the people running the site to fix the glitch. Most people have better things to do and will simply take their business elsewhere -- and that's what I'd recommend, as well.

You can see a list of short, mostly nontechnical definitions of this and other Web server error codes at http://webopedia.com/quick_ref/error.asp .

--Rob Pegoraro

Rob Pegoraro attempts to untangle computing conundrums and errant electronics each week. Send questions to The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 orrob@twp.com.