I ran into this problem when I tried to re-open a solution I did a while back when labbing with Fluent NHibernate and SQLite.
Behind the cryptic error message lies and easy solution; I was running the 32-bit version of the SQLite-driver and runtime. That’ doesn’t fly on my Windows 7 64-bit machine.
Here is a more through description and here is a link to the latest version of SQLite that will get you all the version (32 and 64 bits) of the SQLite.