I'm using DPP 4 version 4.10.0.1 and EOS Lens Registration Tool version 1.10.0 that's packaged with the DPP 4 version 4.10.0.1 installer from Canon site. It's been stable since - I've worked on several of my RAW files since, no issues thus far.
BTW it is not necessary to uninstall and reinstall DPP 4. Simply deleting the mentioned folder fixed the issue at least for me, I did break it multiple times deliberately and tested this fix, .
Glad it worked for you. I figured the lens tool was the offender. I made Canon support aware of my findings. Hopefully they'll find a fix and publish the updated version soon :). Cheers, Raj
