You can use the registry to tweak and troubleshoot your system, but be sure you back up the keys you're hacking before you make any changes. Then, if your changes don't work, you can restore the original data.
To use regedit.exe to back up a key or subkey, select the target key or subkey and choose Registry, Export Registry File from the menu bar. In the Export Registry File dialog box's File name field, enter a filename that will help you recognize the file's contents. (The OS automatically adds the .reg extension.) To restore the original data, open regedit, choose Registry, Import Registry File from the menu bar, and select your file. You can also restore data by double-clicking your backup file in My Computer or Windows Explorer. The .reg file extension is associated with the Merge command, which automatically sends the file's contents to the registry.
To use regedt32.exe to back up a key or subkey, select the target key or subkey and choose Registry, Save Key from the menu bar. In the Save Key dialog box's File name field, enter a filename that will help you recognize the contents. To restore the original data, open regedt32, choose Registry, Restore from the menu bar, and select your file.