[Freebooter]

TFC. or Temp File Cleaner, is a small utility that will clean out all the folders on your computer that house temporary files. The temp folders that TFC will clean are the Java, Windows Temp Folder, and the Internet Explorer, Opera, Chrome, and Safari caches. This tool will clean the folders for all accounts on the computer including the Administrator, NetworkService, and LocalService accounts. You can also read my tutorial to learn how to boost performance of Windows. I also created program called SysPerf to boost performance of Windows and Network. All the Url links are below.

"Temp File Cleaner"
http://www.bleepingcomputer.com/download/tfc/

[BHCPU] Tweaking & Optimizing Windows -Tutorial by Freebooter

[BHCPU] Boost Windows O/S & Network Performance by Freebooter

[Freebooter]

I use CCleaner and ASC 8. I'll help you get CCleaner and ASC 8 Professional for free. PM me!

CCleaner is free software and i wont advice using Advanced System Care program i repair few computers in which this program cause errors.

[ITEngineer]

What errors in particular?

I would take a stab and say, registry related errors.

[Freebooter]

What errors in particular?

Registry errors like wrong or missing files associations or programs cannot be uninstall because of damage or missing uninstall registry values or keys.

[Jeffrijs]

I would suggest ccleaner.