I have been downloading several large RARed files and every time I try to extract a file from within the compressed archive I am told that there is a CRC error and that the file can not be extracted correctly. Why is this? I doubt that every file I download is irreparably damaged. Is there anyway to repair the files? I remember doing this once before long ago, the particular FTP server had a nasty habit of corrupting files so a small utility was made available to correct the damage.
Unfortunately, yes, the files are all corrupted. CRC stands for cyclic redundancy check. It’s a (rather old) error checking protocol.
If a file fails it means that some of it’s bytes are wrong and there is no way to figure out what they should be.
It usually means that you do not have the complete file as originally zipped (RARed in this case). A redownload of the file usually fixes this, unless the source itself is a corrupted or incomplete file (which is often the case if you are downloading from unreliable sources).
Another reason for this is that if you are downloading through your browser, it often just drops the download connection and leaves you with an incompletely downloaded file, without offering any indication to you that the file wasn’t completely downloaded from the server. If this applies to you, first download Getright from http://www.getright.com and use Getright for all your file downloads. It’s extremely easy to use and very effective in such cases, because it always first determines the actual file size.
PKZipFix (from pkware.com) used to, sometimes, repair corrupted zip files. I doubt it works on RAR files.
Are you using WinRAR, or different program? I used to use WinACE with RAR files, but I found that it had problems with some RAR files. If you’re not using WinRAR, try using it with those files.
Yes! I was using WinAce, then tried WinRAR and it worked. Thank you very much!
No problem!
I downloaded the latest version of WinACE recently, and it mentioned a bug fix for RAR files. I still kept the RAR association to WinRAR though, so I can’t say if the bug is really fixed.
Off-topic addendum: “Cyclic Redundancy Check” is one of those great computer phrases you can use to make it sound like you’re a genius if you work with 'puters.
Example: “Boy, am I bushed. I had to do a Cyclic Redundancy Check today at work.”
Utter rubbish, but sounds great.
RR
Oh sure RiverRunner, expose me for the fraud that I am! 
Ancient Chinese secret ah?