Read Part 1 or Part 2 of this article
Last Known Good Configuration
Have you ever had a windows error which caused a reboot? If you have you probably were presented with a black screen that offered several options (none of which seem like a good idea at the time). The screen offers several options: Safe Mode, Safe Mode with Networking, and Last Known Good Configuration.
Exactly what is Last Known Good Configuration? I'll tell you now it isn't a life saver, but it could come in handy. Each time your computer boots normally there is a backup made of the Hkey_Local_Machine\System\CurrentControlSet tree and its' sub keys. Choosing Last Known Good Configuration causes Windows to load that backup in place of the current registry file during boot. If the original problem was a registry issue that affected that tree and/or sub keys then you may be able to recover by choosing that option.
Generally I find that registry entries related to hardware affect this tree, so if you've made a hardware or driver change before the problem this may be a wise choice. If you haven't made any hardware or driver changes I would stay away. It is in no way a substitute for a good backup!
CLSID
There were a few readers who discovered entries labeled CLSID as they were exploring the registry. CLSID is short for Class Identifier or Global Unique Identifier (GUID). Here is an example of a CLSID - {6B9228DA-9C15-419e-856C-19E768A13BDC}. A long (128 bit) number that means nothing to you or I. In actuality it is a unique number which references an executable on your computer. Here is an example. The Vista Sidebar allows you to add Gadgets to your desktop. If we look in Hkey_Classes_Root we will see the following:
So we know the CLSID Windows is using for gadgets. Let's have a look around and see what file extension Windows associates with sidebar gadgets.
I know not everyone has Vista. This was just an example. Look around. Find an extension you are familiar with. Use Edit>Find to locate the associated program.
.reg files
You may run into files on the internet or through emails that have the file extension .reg. These files are meant to add, change, or delete entries from the registry in a way that is much simpler than explaining how to navigate to a specific key(s) and make a specific change(s).It is a simple text file created in a specific format. These files can run the gamut from innocent to evil. Be VERY careful if you are ever told to download or execute a file with this extension. Only do so if you are absolutely sure of the source, trust the source, and have a current backup. These can get you in a lot of trouble if you aren't careful!
Let's wrap it up
I hope you've learned a little about the Windows Registry over the last three issues. At least enough so you aren't scared when someone mentions the word "Registry"! I use a program named RegCool in place of the built in registry editor. I've grown to rely of this program. Unfortunately it wasn't compatible with Vista. Thankfully the author recently updated the program! Windows Regedit program provides search results one at a time. This can make removing left over software entries a very lengthy process. What I like about RegCool is it gives search results all at the same time allowing you to delete groups of keys simply. If you would like to try RegCool you can find it here.