You've got a conflict that needs to be resolved in svn. If it's not one of the files, check if it's a tree conflict.
From the SVN 1.6 release notes:
Subversion 1.6 recognizes a new kind of conflict, known as a "tree conflict". Such conflicts manifest at the level of directory structure, rather than file content.
Situations now flagged as conflicts include deletions of locally modified files, and incoming edits to locally deleted files. Files and directories which are victims of a tree conflict cannot be committed before the conflict is marked resolved.
Note that Subversion is still treating renames as a "copy+delete" operation, so file renames causing tree conflicts can only be detected in terms of file additions and deletions. Because of this, false positives during tree conflict detection are possible.
To facilitate tree conflict detection, attempting to commit the deletion of a file which has already been deleted in the HEAD revision now causes an error. In Subversion 1.5, this was treated as a no-op, potentially resulting in "empty" revisions which contained no changes.