I followed the internet tablet school instructions. First, I updated the firmware, that worked fine. Both before and after, I could not install anything. The log does not show any errors. I disabled the catalogs one by one and never was able to update.

I purchased the unit second-hand and it seemed to work fine except that I could not install or update and applications. The applications the original owner had on the unit worked until I updated the firmware; now I have lost those (not that I cared about those particular applications).

What should I try now?

I now am at least seeing my log errors:
hildon-application-manager 2.1.16
E: Failed to fetch http://catalogue.tableteer.nokia.com..././Release.gpg Could not connect to catalogue.tableteer.nokia.com:80 (1.0.0.0). - connect (101 Network is unreachable)
E: Failed to fetch http://www.fbreader.org/maemo/dists/diablo/Release.gpg Could not connect to www.fbreader.org:80 (1.0.0.0), connection timed out
E: Failed to fetch http://catalogue.tableteer.nokia.com...ablo/./Release
E: Failed to fetch http://catalogue.tableteer.nokia.com..././Packages.gz Could not connect to catalogue.tableteer.nokia.com:80 (1.0.0.0), connection timed out

Looks like an issue with your network configuration.

I'm suspicious of those ip addresses (1.0.0.0)