What's a C-Notice?

I recently withdrew some fundage from my online mutual fund account, and got the message (paraphrasing): “You may withdraw money, but mandatory tax withholdings will be applied because there is a C-Notice. You will need to contact the IRS to resolve the C-Notice issue.”

I got my money so I’m not too concerned, but what is a C-Notice, why is there one on my mutual fund account, and what do I do about it?

C-Notice:

Bugger! Stupid gummint beaurocrats.

Well I guess I better get on the horn with my accountant.