By Lou Dolinar
Updated Feb. 14, 2006

I had my monthly run-in with the Windows Registry last week. My daughter Ann was trying to install a new HP printer on her PC, and the installation froze about two-thirds through. We got an error message saying that the folder HP was trying to install already existed, and that Windows couldn’t overwrite it.

Well OK. I found the folder, cleaned it out, and tried to delete it manually. File not found. Windows was confused: It knew where the folder was in order to display it on screen, but couldn’t, for some reason, find it to delete it or overwrite it. If Windows were a person, I would send it to a psychiatrist. But Windows being Windows, I figured out rather quickly that the problem lay with the Windows Registry.

The Windows XP registry is a lot like an old-fashioned hotel registry. People (actually, programs and settings) fill out a little card when they check in. The card is filed away, and carries critical information, like room numbers, billing, and phone extensions. For programs, the Registry handles all manner of detail , including such trivia as the header text that says “Microsoft Internet Explorer” at the top of your browser.

Drop the card file on the floor, and scramble the cards, and suddenly there’s chaos at XP Suites International. Who the heck is in room 403? What the phone number? Where do we send the bill? The chaos can be minor, e.g. a couple of cards get out order, and a phone call gets routed to the wrong room, analogous to what happened on Ann‘s computer. Or the cards can be scrambled altogether, and its time to call for the lawyers. When you reach this stage in Windows, the computer may not start.

How does the Registry get in trouble? Installing an application, a driver, or an update can create a registry entry that conflicts with an existing one. References to files that don’t exist, or that are in different directories, are another problem.

Conversely, uninstalling a program or driver may remove an entry that’s required by another program. Even the best behaved installers leave behind junk that clutters the registry and slows down access to it.

Oh, and if you’re a real pro, you can screw up the Registry manually, by wading in with Regedit and changing a critical setting

Most people know better than to mess with the Registry, but there are ways of approaching it gingerly. Something like radioactive waste, where you use the computer equivalent of remote control arms shielded by leaded glass.

For Ann’s problem, I used the registry cleaning tool in Norton Systemworks, though registry cleaners all work on similar principles: it parses the Registry, and looks for contradictions and dropped references. I’ve had equally good luck with the Microsoft’s freebie Regedit (suitable for pre-XP versions of Windows), as well as Registry Mechanic (http://www.winguides.com/regmech/), CleanMyPC (http://www.registry-cleaner.net/), and Systemworks clone TuneUpUtilities 2004 (http://www.tune-up.com/?ap=2001). There are so many similar registry that you could probably download a lifetime supply of free trial offers.

Systemworks found the problem with Ann’s Registry, along with about 100 other issues. If you’ve never run a registry cleaner, don’t let this kind of stuff freak you out. Most Registry problems only slow the computer imperceptibly, and it takes a lot of them to deliver a measurable performance hit. My favorite fully free registry cleaner is EasyCleaner, from ToniArts (http://personal.inet.fi/business/toniarts/ecleane.htm).

You can make major changes in how Windows behaves by altering the Registry deliberately. Fortunately, you don’t have to do this by hand. For example, Installation programs and Control Panel items are generally manipulating Registry settings, and various add-ons can extend that functionality.

Try Microsoft’s TweakUI, (http://www.microsoft.com/windowsxp/pro/downloads/powertoys.asp) for a free taste (Check out the other Power Toys too). It will alter dozens of Registry settings to your preferences, including animation of various screen functions , mouse behaviour, menus, Internet Explorer setup and more.

If that’s not enough for you, see http://www.kellys-korner-xp.com/xp_tweaks.htm for another 300 or so tweaks. Where TweakUI is a standalone program, each tweak on Kelley Korner is a short Visual Basic Script that you can download and run to install. Some of this stuff can be a little silly (how about a script that can install TweakUI as a Control Panel item?) or or marginal use (make Google the default search engine in IE).

Do you ever need to edit the Registry manually? I don’t usually approve, but when your system’s totally hosed, it might be worth a shot. The only common reason is the growing spate of spy ware, most of which alters the Registry in subtle ways to perpetuate itself. While some public spirited folks write open source programs that get rid of this stuff (see www.Merijn.org for CWShreddwer, one of the best) there aren’t universal solutions and sometimes solutions lag behind threats. At that point, you may have to go onto a newsgroup like http://boards.cexx.org/ or http://forums.spywareinfo.com/ for help, which often involves changing a registry key. Before you do that, first check out the Elder Geek (http://www.theeldergeek.com/windows_xp_registry.htm) for tips on how to edit and back up the Registry.