I have version 2.5-os2008 installed. Application manager shows an update (version 2.5.1-os2008) but I'm unable to install it. Application Manager says the update is corrupted. I wonder if your trouble installing is related.

You might try installing a previous version. Look here.....
https://garage.maemo.org/frs/?group_id=29
scroll down for the os2008 versions.
You'll have to download the .deb file and save it locally, then install.