1. You've run CCleaner, and now there's an issue with
Windows.
In the rare situation where your use of CCleaner has caused a
problem with Windows, you can easily repair the situation using the
backup you made before you ran CCleaner.
These steps will set the Registry back to the way it was:
a. Using Windows Explorer, navigate to the folder with the
Registry backup (a file with the extension .REG). By default,
CCleaner stores these backups in your My Documents folder.
b. Double-click the Registry file. You are prompted to confirm
the action:

- Registry add confirmation
c. Click Yes to restore the Registry.
2. When you try to restore a Registry backup in Windows
XP, it fails. (Advanced)
Windows may no longer recognize .REG files as belonging to the
Windows Registry (a file association error). This procedure may fix
the problem:
a. Download the third-party file REG File Association Fix at http://www.dougknox.com/xp/fileassoc/xp_regfile.zip.
b. Unzip this file to your desktop.
c. From the Windows Start menu, click Start,
and then click Run.
d. In the Run dialog box, type regedit and then
click OK. The Registry Editor appears.
e. In the Registry Editor, click File, and then
click Import...
f. In the Import Registry File dialog box, browse to the
desktop. Select the Registry file you unzipped in Step 2, and then
click Open.
Note: We provide this solution for information
purposes only. This is not a recommendation or endorsement of
third-party software.
3. CCleaner closes after it finishes the cleaning
process.
You can choose whether you want CCleaner to quit or remain
available once you've finished running the Cleaning process:
a. In CCleaner, click the Options icon at left, and then click
Advanced.
b. Select or clear Close program after
cleaning.
4. Issues you have selected to be fixed continue to
appear in the Issues list on later scans. (Advanced)
This may be a result of errors with Windows registry
permissions. You may use the Windows utility regedit.exe to change
these. But this is not recommended for anyone to do, unless you're
an advanced user.