From the McAfee Help section dealing with Shredding :
You can specify how many times (up to 10) that you want to shred an item: 1 (Quick) is the fastest and 10 (Complete) is the most secure. The more times you shred an item, the more confident you can feel knowing that your private information cannot be recovered.
A summary screen shows you the total number of items shred and any items that cannot be shredded. If you minimize your McAfee software while the tool is running, an alert shows you the total number of items shred and any items that cannot be shredded.
You can also shred an item directly from Windows Explorer with a manual shred.
Before you shred any files or folders, make sure that you no longer need them. Once you shred a file, it is gone forever and cannot be restored.
In theory, there may be a way to recover something that has been shredded. Everything though depends on how thorough the shredding was, and how much time has passed since it was shredded. "Shredding" is the process of overwriting data on disk to make it more or less unrecoverable. If the data is overwritten only once or twice then it can be recovered, with some data loss, even by freely-available recovery tools like Piriform's Recuva. If the data is overwritten many times then only specialist digital forensic tools stand a chance of recovering it.
The McAfee Shred options indicate how effective shredding might have been -
Recuva might get something back if the Shred option chosen was Quick (see below), but after something has been shredded the space it occupied becomes available for general use. So a very-recently shredded file might (perhaps) be recoverable, but after a few days the disk location could have been used and re-used many times.
As an experiment I copied a small gif file to a Temp directory and shredded it using Basic shred type. Recuva was unable to locate it, which means the chances of recovery even from a Quick shred are not good.
The only hope of getting back a shredded file is if user files have been copied to a backup location (even copying to a different partition on the same disk is better than nothing). If you shred a system file (and you shouldn't) then Windows keeps its own copies of those files. Otherwise .... no. Shredding is, to all intents and purposes, destructively final.
Edit - Wikipedia is quite informative on tech matters. See
Second edit - Recuva found the file using its Deep Scan option (which can take a very long time to run unless you have a small-capacity HDD) but reported it as unrecoverable and overwritten with a newly-created temp file. So don't hold out too much hope for getting a shredded file back even if you only used minimal shredding.
Message was edited by: Hayton on 31/12/12 00:09:09 GMT