errors in pg_restore on windows?

Using PostgreSQL 8.3 on Windows, I make a backup like this:
pg_dump -U postgres -C -d -D -Fc -f ispaaa-pg.bak ispaaa

Then restore like this:
pg_restore -U postgres -C -d template1 -v -Fc ispaaa-pg.bak

And I get lots of these errors:

pg_restore: creating TABLE voip
pg_restore: creating FUNCTION pldbg_abort_target(integer)
pg_restore: [archiver (db)] Error while PROCESSING TOC:
pg_restore: [archiver (db)] Error from TOC entry 21; 1255 16419
FUNCTION pldbg_abort_target(integer) postgres
pg_restore: [archiver (db)] could not execute query: ERROR: could not
load library "C:/Program Files (x86)/PostgreSQL/8.3/lib/pldbgapi.dll":
The specified module could not be found.

Command was: CREATE FUNCTION pldbg_abort_target(session integer) RETURNS SET
OF boolean
AS '$libdir/pldbgapi', 'pldbg_abort_target'
...
pg_restore: [archiver (db)] could not execute query: ERROR: function public.pld
bg_abort_target(integer) does not exist
Command was: ALTER FUNCTION public.pldbg_abort_target(session integer) OWNER
TO postgres;

It looks like a packaging issue with the windows installer - these
commands work fine for me on Linux.

Thanks,

Dan