pg_dump failes due to invalid memory request

Hi,

I just tried to call pg_dump for my database this evening, and it fails on one of my tables.
The error it gives in the log is:
ERROR: invalid memory alloc request size 3221230573

So at this point what do I do?

What I have done:
I reindexed the table sucessfully, and it made no difference.
I tried grabbing all the rows around the last row that was sucessfully dumped through a select statment. That worked sucessfully.

How do I test/fix this?
I am assuming something is corrupted but I am not sure how to figure out what. I have had nothing in the logs to indicate a corruption. Now the only thing I can think of is that this particular table has 2 custom data types that are both toastable. I am guessing that number indicates a bad header value at the beginning of one of the custom data types.

Please help!

Thanks,
Morgan