I uninstalled Apex 4.2.5 and installed 4.2.4, as this is a version I have installed before without any problem, but the issue persists. An information I didn't specify would be that this is installed in an e-business database with the demo Vision data. I didn't think it pertinent before, but now I think it may be the reason for this issue somehow.
EBS is version 12.1.1 (will be upgraded to 12.1.3)
A common problem is that the apxchpwd.sql script being executed is the wrong version. Verify you are running the apxchpwd.sql script from the correct apex distribution directory (not the apex directory that included with the db).