Did you ever get to the bottom of this? Flash Builder just crashed on my machine and now refuses to open—giving this error verbatim when I try to launch it from a command prompt.
EDIT: Google led me to this post, which mentions deleting the
C:\Users\[USERNAME]\Adobe Flash Builder 4.7\org.eclipse.core.resourcesdirectory (see the 2nd comment by christoph). This allowed Flash Builder to start again, but I had to import all my projects (thanks, Adobe, for wasting an hour of my time today).
Thanks stenrap2.. Only an hour wasted? That's good!
I did solve it yes - I did something similar to http://forums.adobe.com/message/4611386.
Although, I'm not sure why there's a cleanup tool instead of actually fixing the issues and costing developers time and money.
I just had this same issue.
I looked into what was suggested in the link Stenrap2 gave [removed by moderator], but instead of deleting the whole
C:\Users\[USERNAME]\Adobe Flash Builder 4.7\.metadatafolder, I went into there in
.plugins\and deleted the
org.eclipse.ui.workbenchfolder and it allowed me to start Flash Builder up again without losing my projects and settings. I did lose the previously opened files, but apart from that, everything is there.