Ok, so you are working with a custom build from svn not from the official release files. I know this because SubSonic stuff wasn't in the last release.
I'm pretty sure you can solve this by commenting out the provider shown in your post from Web.config. In fact if you are using MS SQL, you can comment out all the other providers except the one for MS SQL.
Also there is a setting in the appSettings section of Web.config
<!--
Set this to your corresponding db platform
subsonicMSSQL
subsonicMySql
subsonicSQLite
subsonicPostgreSql
subsonicFirebirdSql
-->
<add key="SubSonicProvider" value="subsonicMSSQL" />
make sure this is set to the db you are using. Like if you are using MS SQL and somehow this is set to SQLite it could also cause the error.
Hope it helps,
Joe