I have an SVN repository (hosted on Dreamhost) with needs-lock set on binary files. It sometimes happen that, while committing files locked and modified by me, the commit fails
On Windows, I fixed the problem by the following steps:
1. Launch Repository Browser by clicking "Repo-browser" in the menu.
2. Locate the locked file.
3. Right click your mouse on the locked file.
4. Click "break lock".