could not load library unknown error 14001

CREATE FUNCTION uuid_generate_v1() RETURNS uuid AS '$libdir/uuid-ossp', 'uuid_generate_v1' VOLATILE STRICT LANGUAGE C;

I gоt error 'could not load library unknown error 14001' when i run this script. What is this error and how can i rectify it? Postgres user has got full access to postgresql folder. I also tried to run it on real Windows 2003 Server machine with the same result.

library is at the 'C:\PostgreSQL\9.1\lib\uuid-ossp.dll'

postgresql-9.1.2-1, WindowsXP SP3 (VirtualBox).