Recently, I've noticed cygwin svn getting a LOT of errors during 
operations.  I think this started when upgrading from 1.7.14 to 1.7.15, 
but I can't say for sure.  The nature of these errors are as follows:

$ svn up
Updating '.':
svn: E200030: disk I/O error, executing statement 'RELEASE   s6'
svn: E200030: sqlite: unable to open database file
svn: E200030: sqlite: unable to open database file


$ svn cleanup
svn: E200030: disk I/O error, executing statement 'RELEASE   s79'


Sometimes the errors happen, sometimes not.  It seems to be about 50% of 
the time svn has this type of error now.  I've tried running the exact 
same version of SVN (the command-line version shipped with TourtoiseSVN) 
on the exact same working copies and I don't have any errors.

I'm not running any anti-virus (I was, but I uninstalled it a couple of 
days ago to make sure it wasn't causing this trouble).