Some users have reported issues on self hosted WordPress sites. This issue affects older versions of WordPress (< 2.7).
A new app version will be available as soon as possible to address this issue.
In the meantime we have pushed out the latest beta, 0.9.0.199, which includes more user-friendly error messages to help troubleshoot. To download the new beta, just point your browser to http://blackberry.wordpress.org/install and overwrite the current installed app.