I've been reading all the threads on problems with IR samples in the Proverb plugin as I have had trouble myself. I could drag individual files or a folder of files to Proverb's interface and they would all install correctly and I could use them as you would expect until I closed DP down.
When I relaunched DP (even if I had saved the project), the User, Shared and Project menus would be greyed out and only the Factory IRs could be selected. I haven't had DP for long so after trying everything I could think of I put in a support ticket to MOTU.
Apparently it is a bug in the windows version, this is the reply I got this morning from tech support.
"Thanks for writing. This is an bug that I have reproduced and passed on to our dev team. I'll keep you updated as to whether there's a workaround or when a fix is released".
MOTU support is excellent, I only put the ticket in yesterday.
I hope this post will help other DP users and save some hair being ripped out!