As a favour to anyone else out there that may hit this one.
svn: Can't open file next-ids: The process cannot access the file because it is being used by another process. If you see this message on your Subversion server - it's likely that your real time anti-virus software has got a hold of the next-ids file while it was being written, locking Subversion out.
One to be updated in the future. Will create a category for Theory and Fundamentals at some point. Having written a fair amount of high-level language code, VB6 and C#, I figured getting to grips with the fundamentals might not be a bad idea.
Here are a few titles that have 'moved me' in this direction.