I suspect RSSOwl's installer has a problem with the installed version of the JRE, and is ignoring the Java 6 update Not every Java update replaces the JRE that got installed with the SDK.
Try downloading a copy of
JavaRa from
http://raproducts.org. First have it check for (and install) any updates. Once that's finished, have it remove any older versions of Java. That should clear up the problem.
JavaRa is a simple tool that does a simple job: it removes old and redundant versions of the Java Runtime Environment (JRE). Simply select "Check for Updates" or "Remove Older Version" to begin. JavaRa is free under the GNU GPL version two.
If that doesn't work, you could try uninstalling all your Java instals and updates manually using Revo. Then download and install a fresh copy of the JRE from here:
https://cds.sun.com/is-bin/INTERSHOP.enfinity/WFS/CDS-CDS_Developer-Site/en_US/-/USD/ViewProductDetail-Start?ProductRef=jre-6u15-oth-JPR@CDS-CDS_Developer
If you do actually need the full SDK, you can also get that from Sun's website.