svn: Your file or directory is probably out-of-date

One of the most tedious bugs in Subversion, ever, is this one. If you want to commit changes to your working copy, and the response of svn is :

svn: The version resource does not correspond to the resource within the transaction. Either the requested version resource is out of date (needs to be updated), or the requested version resource is newer than the transaction root (restart the commit).

If you stick with standard advice, trying to update your working copy you'll find out something interesting: Nothing is out of date! You just can't commit!!!

One solution that I found, but I don't know all the consequences of doing this so DON'T BLAME ME if you lose important local properties in your repository is the following :
1) Go to the directory in your working copy that contains the problem file.
2) Delete .svn/all-wcprops from there.

That's it. Commit and be happy. PS: All I can say is that this has not crashed any of my working copies yet.