A set of files called the "registry" is at the heart of Windows. The registry is a huge database, typically containing thousands of entries.

When Windows is started the registry is scanned (one reason Windows seems to take so long to start), and various information strings and settings are read. This information is used to start up all the applications which open automatically when you turn on your computer, and to configure all those applications to the settings previously chosen for them.

The important files in the registry are called system.dat, user.dat, system.ini and win.ini.

It is likely that your registry will be too large to fit onto a floppy disk. I've seen registry files on the computers of some SeniorNet members of more than 6 Megabytes.

Not only is the registry critically important, it is also quite vulnerable. A corrupted registry is perhaps the single most common cause of computer malfunction.

Installing New Programmes

One of the most common culprits in causing registry corruption is a badly written programme. This is why people most often find they suddenly have a computer problem just after they have installed a new programme.

Next time you are tempted to install a new programme to "see what it's like", just remember that the installation process will almost certainly make changes to your registry. It may add hundreds of new entries, and make many changes to entries already there. If the person who wrote the programme hasn't been scrupulously careful and thoroughly tested the programme's code, you may find some unexpected and unwelcome changes in your computer's behaviour.

Uninstalling Programmes

The safest way to uninstall (remove) a programme is from the control panel, using the "install/uninstall programs" facility (access via Start/Settings/Control Panel).

Don't be tempted to simply delete the folders which contain the files for the programme you want to get rid of. If the programme designer has done a good job, there will be a special uninstall routine, accessed from the control panel. This routine will attempt to remove unwanted entries from the registry, as well as the programme's own files and folders.

If you removed the programme's files and folders in an attempt to get rid of the programme, you will have removed the special uninstall routine, and you will have no way of removing the appropriate registry entries. If you've done this by mistake, the best plan is to re-install the programme again, then uninstall it properly.

However, even when using the correct method, it is highly unlikely your computer will be restored to its previous condition, and some traces of the programme will be left behind. Some changes may not be easily reversible, especially if some files (eg .dll files) were overwritten with different versions during the installation process.

Playing Safe

Perhaps the best way of avoiding problems is to resist the temptation to install new software out of curiosity. If you're tempted to install something, ask yourself whether you really need it, and has it come from a reliable source.

To be continued ... How to save a copy of the registry.
John Selby.

First printed SNN Newsletter November 2001