How to manage CCleaner

CCleaner have many options to clean my computer.But How can I know what to clean,what to delete,what to fix?I have heard of people having trouble with their computer after a clean up,have your registry fix or delete some information that is important to keep.Can there be some explanation of what can be deleted or fix before taking action.The words "carefully select what to delect or fix makes me think that not everything that shows up can be fix.

Registry it is best to leave it be, unless you know FOR SURE that you don't need the item

For what the different selections in the cleaning sections there's a guide

Windows Tab - http://www.piriform.com/docs/ccleaner/ccleaner-rules/windows-tab

Applications Tab - http://www.piriform.com/docs/ccleaner/ccleaner-rules/applications-tab

you can Find Exactly what is cleaned in the applications tab by running the following in your Operating systems Run box (Including the Quote marks)

"C:\program files\ccleaner\ccleaner.exe" /export

where c:\program files\ccleaner\ is the location of your ccleaner program

After that you can open winapp.ini and/or winsys.ini in a text editor and you'll see entries such as

[Adobe Acrobat Reader 7.0]
ID=2020
LangSecRef=3021
Detect=HKCU\Software\Adobe\Acrobat Reader\7.0\AVGeneral
Default=True
RegKey1=HKCU\Software\Adobe\Acrobat Reader\7.0\AVGeneral\cRecentFiles
FileKey1=%localappdata%\Adobe\Acrobat\7.0\Cache\Search70|*.*
FileKey2=%ProgramFiles%\Adobe\Acrobat 7.0\Reader|*.bak
FileKey3=%ProgramFiles%\Adobe\Acrobat 7.0\ActiveX|*.bak
FileKey4=%ProgramFiles%\Adobe\Acrobat 7.0\Reader\plug_ins|*.bak
FileKey5=%ProgramFiles%\Adobe\Acrobat 7.0\Reader\Updater|*.bak

Detect or DetectFile will tell you where ccleaner is looking to tell if an app is installed

RegKey and FileKey tell you what is deleted