VST instrument suddenly unmapped

My Cubase alwasy get crashed when I load too many VST instruments. I assume the reason is lack of the memory. However, yesterday I met a weird problem. I finished a project with many VST instruments as usual. I saved Cubase file and mixdowned the audio file successfully, and closed Cubase. 10 minutes later, I found I need to edit the music again. Then I tried to open the project file but Cubase crashed. I restarted and tried again, It still crashed. I thought it should be lack of the memory. I thought updated to the latest Cubase 5 maybe help. Then I did it. After updating, I can open the project file, but one of the VST instrument, Omniphere, showed “Unmapped”, the midi tracks which use Omniphere missing the connection. Other data looked fine.

When I work on a new piece, I usually save as a new project every other days. So, I have 4 earlier versions for the same music work. It means I have five different project files. Four of them did not in use when Cubase got crashed. However, all of them shows “Unmapped” error message now for the same VST instrument, Omniphere. It doesn’t make sense to me. If the crash made the project file got corrupted, the other four project files should be fine. And for all of them, I can not load another copy of Omniphere VST. It didn’t response when I tried to load it. I removed Omniphere instrument track, and disconnect all midi tracks which use Omniphere. Then I can load a new Omniphere again.

My problem is that I do not remember what patches I use in Omniphere. Even I load a new Omniphere, I can’t get my original idea back, since there are thousands of patches there. My questions are:

  1. Is it possible that I can fix the unmap error to reconnect the original copy of Omniphere VST in the project?
  2. If not, is it possible that I can find what patches I used before in the Cubase project file, such as a log file, or VST information which saved together with the Cubase project file?
  3. What can I do if I meet the same problem, the saved file can’t be open again?