Newbie DDL problems in Portal, please help

The situation is defining tables in Oracle Portal Navigator. I am currently trying to work backwards to unscrew up what someone already has....so call it 'redefining'. I had to add more/alter columns, put different datatypes in, etc. No constraints, no foreign keys, just a primary key and I've even unselected that. I've tried to isolate as much as possible. The error I'm getting is not a standard SQL error and I cannot find any record of it on the net.

Just to paint a better picture :)

http://www.imagestation.com/picture/...e/fd1a2a1e.jpg

The error I get is this:

Error: Unable to obtain lock on component ID: 1913231670, version 1 - check status (WWV-01817)


What could this be? Like I said, theres no data in the table, no constraints or keys to conflict with other tables (theres not even data in those tables). When I manipulated the other tables, I didn't get this error

All advice welcome! :D