I have an update on this bug:
I recently purchased a new computer (a MacBook Pro

), and, after installing the following items (all, except windows, are latest downloads from the web - I never store downloads), in sequence, Aptana works fine*:
-- Windows Vista SP1
-- Several unrelated softwares, like browsers
-- Ruby 1.8.6 using the one click installer
-- Fully updated gems
-- Gems: rails, mongrel, mysql, capistrano
-- TortiseSVN
-- Aptana
-- RadRails, PHP, Air, and iPhone plugins
-- Subclipse plugin
* Actually not quite. When I do interesting things with SVN (particularly setting properties it seems, though I haven't completely isolated that), Aptana sometimes throws an error telling me that I have an outdated version of SVN which cannot handle the repository format any more. Since TSVN always is able to, I figured there must be a copy of SVN in subclipse, and that by installing a full copy of SVN on my system, I would be able to solve this problem.
So I did. I grabbed and installed the tigris build of 1.4.6 (since they didn't have a 1.5.0 build) for Apache 2.2 (note I do not have apache anything installed - I just figured using the latest would be best). It installs great, and doing 'svn --version' in my cmd now shows it (though I don't know what it was showing before). Started up Aptana, which then opens my project, and bang, it crashes with this error.
So that may provide some more information as to what is causing what....I will try uninstalling my packaged svn and see if that saves Aptana.