File node 'edit' page will not load

Issue Summary

This is a cross posting of #407650 (in the FileFramework issue queue)

When a user other than uid 1 attempts to edit a file node, the page never loads. Using the mysql interpreter and running 'SHOW FULL PROCESSLIST' shows that a query like this one is the problem:

/* username: rdf_db_rdf_query */ SELECT g.uri g, s.uri s, p.uri p, o.uri o, t.uri type, d.lang, d.data FROM rdf_data_file d
LEFT JOIN rdf_resources g ON d.gid = g.rid
INNER JOIN rdf_resources s ON d.sid = s.rid
INNER JOIN rdf_resources p ON d.pid = p.rid
LEFT JOIN rdf_resources o ON d.oid = o.rid
LEFT JOIN rdf_resources t ON d.tid = t.rid
WHERE (s.uri = 'bitcache://39eab0acaea321a65cd889182b8f49af2dce1b8b') AND (p.uri = 'http://purl.org/dc/elements/1.1/extent')
ORDER BY d.did ASC

Running 'SHOW FULL PROCESSLIST' multiple times shows that the values of s.uri and p.uri are always changing. The query takes .13 seconds when run by hand, but whatever is happening in drupal is causing it to just run and re-run with different values.

I'm using:
rdf 6.x-1.x-dev
fileframework 6.x-1.0-alpha4
bitcache 6.x-1.0-beta2
I was using the latest non-dev version of rdf, and tried upgrading that to see if that would resolve this issue - but it didn't.