I have a collection of USB drives in my laptop bag, as I suppose we all do, and recently I wanted to use one to give someone some files. This wasn't a temporary hand-it-over-they-copy-get-it-back scenario, so I wanted a pretty much empty drive. I found one with only 3 files on it, but the bad news was one of the files was called ReadyBoost.sfcache. That means at some point I had put the drive into my machine and told Windows 7 it could use it to speed up my machine. That's a good thing, and I'm a ReadyBoost fan and all that, but I wanted to use the drive for files and it was pretty much all filled with the cache file.
I tried deleting it, but no go. I tried ejecting the drive and putting it in again so I could say no if I was asked about using it, but I should have realized I hadn't been asked earlier when I put it in so not surprisingly I wasn't asked this time either. A little searching revealed the trick. Put the drive in, open My Computer, right click the drive and choose Properties. Go to the ReadyBoost tab. Presto!
![](http://www.gregcons.com/KateBlog/content/binary/noreadyboost.jpg)
Check "Do not use this device", click OK and tada - the cache file disappears and I have my drive back.
Kate