I've had the same issue running EWF with StreetDeck , its seems that even though you specify D: as the data path and data is written to D: StreetDeck still need to reference C:\MyDocuments\............\User\StreetDeck . What I found that works is after opening StreetDeck at least once, just copy not move your SD data path to D: then specify your data path to D: using "edit media path".
Honestly though I'd suggest running EWF on both C: and D: or leaving your StreetDeck data on C:. Lets say StreetDeck crashed and was unable to start after the crash. If you had your StreetDeck data on D: with ewf disabled, rebooting the system would not fix the issue as data had been written to D: (this has happened to me on a few occasions)
I've had so many issue's with StreetDeck crashing then not being able to start requiring a reinstall of StreetDeck or even corrupting my OS. Now I run EWF and HORM on my C: drive with my StreetDeck data folder residing on C:. It does have a few drawbacks but they are far outweighed by the negatives of not running EWF and HORM.
Also see this post Question for Chuck HORM