MADISON, Wis. (AP) -- About $1.6 million in financial aid and tuition refund checks didn't arrive on time. That's left some 600 University of Wisconsin-Madison students waiting for their money. The checks are for varying amounts from about $100 to $10,000.

U.S. Postal Service spokeswoman Marge Oehlke says the post office is investigating what she calls a "highly unusual circumstance."

UW official Cathie Easter says a receipt showed the check vendor put the checks in the mail at a Milwaukee post office August 29th.

Easter says she got about a dozen calls yesterday that students received their checks, but it's too soon to say whether the problem has been resolved.