Postgres wont drop foriegn keys on tables.

I am having an odd problem that I have seen before. It usually clears itself after I restart postgres.

I am attempting to drop an foreign key on a table and it sits for hours and doesn't drop or put anything into the log.

Killing the alter puts an error in, but it doesn't time out and it cause the system to lock at some point.

What can I do to troubleshoot this?

Chris