I've been using svn with 7.0.4 for months, with good success. Now all of a sudden I'm seeing this message. I cross-checked by using Tortoise, and there's no problem connecting to / updating the svn repository: it's something specific to Intellij.
An interesting thing: I am still able to do Subversion | Show History | Compare . So there is no problem with connecting to Subversion from IJ. There seems to be some corner case bug in IJ with Subversion | Compare with the Same Repository Version. I just don't understand why it is all of a sudden happening.