I have been able to successfully play .DSS files and also to successfully replicate and solve the issue you have been having, try the following steps:
1. Uninstall Express scribe through control panel > add/remove software
2. Delete all "scribe" folders in the following directories, before doing this you should create a back up copy of these folders if you have jobs in them currently:
C:\Program Files\NCH Swift Sound
C:\Program Files\NCH Software
C:\Documents and Settings\All Users\Application Data\NCH Swift Sound
C:\Documents and Settings\[user]\Application Data\NCH Swift Sound *replace user with your user name
3. Search computer for "DSS32" using the search function (just press ctrl+f in my computer) and delete any instance of "DSS32.exe"
4. Install Express Scribe from this page:
http://www.nch.com.au/scribe/index.html
5. Try playing a DSS File.
6. If unsuccessful download and install the DSS32 component:
http://www.nch.com.au/components/dss32.exe