davem43624

I've deleted the files & nothing bad has happened. I found that if you right-click the drive you still get a "defrag" option, and it has in fact cleaned up better than it has for years! Nita - I'm running the "Home" edition of Win10, and I think that VSS is turned off by default, so hopefully I won't have any shadowing issues (assuming that is what you meant? Thanks again.

Nita - thanks very much for your reply. I'll try deleting the files & see what happens.

Forgot to say I am using the current free Defraggler (v2.22.995 (64 bit).

Yes, that's right - the opposite to the usual. I have an old external HDD that until a recent Win10 update was seen by Defraggler as an HDD, and was therefore defragg-able. Lately, though, it is being seen as an SSD, and I foolishly "optimised" it, using Defraggler. The drive is now almost filled up with "dfoptimize_nn.bin files (where "nn" is one or more numerals). 2 questions, then: 1. Can I safely delete these files? 2. How can I get Defraggler to treat it as a normal HDD?