You should find a debug.log in one of these directories (I googled them, I don't have a windows bitcoind install);-

C:\Documents and Settings\YourUserName\Application data\Bitcoin (XP)

C:\Users\YourUserName\Appdata\Roaming\Bitcoin (Vista and 7)

You can look in there for errors.

Just because I am curious, search for "ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large" there is a thread going on at github about an odd issue that may or may not be a bug. (https://github.com/bitcoin/bitcoin/issues/5668)

EDIT: And Hazir probably has a good idea .