403 error on commit with checked out WC

I have a user that's having a problem committing changes from his
working copy.

SVN setup: Apache2 on Windows Server 2003 served via https

The error message:

Error: CHECKOUT of
'/svn/repos/!svn/ver/20193/Database/schema/script/setup.sql': 403
Forbidden (https://svn.main)

Permissions look like this:

DBAuthors = MAIN\joe, MAIN\jill, MAIN\bob

[repos:/Database]
@DBAuthors = rw

I don't think permissions are the issue here as the user is in the same
permissions group as two other users that don't have this issue, and the
user is trying to commit from a previously checked out working copy...

so...
1) svn allowed the user to check out on a previous occasion
2) the user should have the same permissions as others that don't
have this issue
3) this is a user who is new to svn, so may have done something odd
in checking out (no idea what...)
4) I have checked the WC URL via 'svn info' and it is correctly
cased etc...
5) the user is using the correct credentials (can read repos, can
checkout)

Why would "CHECKOUT" be forbidden when attempting to perform a commit?
Any other info I should look at?
Any tips/suggestions for other things to look at?
Received on Wed Dec 13 19:55:14 2006