I had the same error yesterday and it was a caps issue (lower-case vs. capital letters). Make sure that the path you try to access has the exact matching lower-case and capital letters (try switching the project). If this doesnt work, edit the file all-wcprops and entries in the local .svn folder of the project root.
After editing the files you might run into error 405, in that case just switch the project (again) to the correct path (again the lower- case and capital letters issue). I hope this will help.
