However, I tried to import a folder into assets in an currently open scene by dragging and dropping, the folder contains some scene's, some textures, in fact the folder was:
Unity gave an error sorry I really should have screen printed it, ah well hindsight.
To the best of my memory an error/dialog box popped up, waring me of too many instances of...
had a long list, the one I think I can remember is monoShader, would that make sense?
Then unity crashed and I submitted a bug report.
Went to reopen Unity again, crashes before it's launched... tried a couple more times, same issue.
Rebooted, Try again. Fail again. Fail better.
Any ideas? I could re-install but it's a trial...
If you want any more information please ask, in fact if somebody has an idea where the bug report is generated before it's sent, I could post that.
It's trying to reopen the corrupted project each time.
Under Windows, hold down the Alt key right after you start Unity running. It should give you a dialog box asking you which project to open. (Option key on the Mac.)
Or, if you have a non-corrupted project on disk already, try double-clicking on one of its scene files to tell Unity to open that instead.