ERROR: invalid page header in block 67 of relation "pg_proc"

I'm getting this error trying to access my database using the pgAdmin III
tool. To the best of my ability here are the steps leading up to this.

Compile and install /contrib/tsearch2

Ran sample queries using the new functions/types (worked fine)

Alter table to include new column

ALTER TABLE ybnet.FreeListings ADD COLUMN idxFTI tsvector;

Use psql to COPY data from text file into table. This initially received
error

ERROR: missing data for column "idxfti"

So I removed the column from the table and ran the COPY again. This worked
fine.

Right after that I started to receive

ERROR: cache lookup failed for function 38151581

Then these errors

ERROR: invalid page header in block 67 of relation "pg_proc"

I stop/start PostgreSQL and that does not clean it up.

This is running on RedHat 7 with 7.4.2 of PostgreSQL