A Very Bizarre Date/time Problem!

Running into a very bizarre problem here. I'm querying a couple of tables based on a date range. Nothing fancy; simply stuff. The query runs fine when I hard-code the dates, but when I use variables, the query just hangs.

This works fine:
SELECT AVG(DATEDIFF(ss, B.SomeDate, C.SomeDate))
FROM A WITH(NOLOCK)
INNER JOIN B WITH(NOLOCK) ON A.BID = B.BID
INNER JOIN C WITH(NOLOCK) ON A.CID = C.CID
WHERE A.SomeDate>='2008-02-09 00:00:00.000' AND A.SomeDate<'2008-02-09 01:00:00.000'
AND DATEDIFF(ss, B.SomeDate, C.SomeDate)<100000


This does NOT: NO clue why :confused:
DECLARE @FromDate DATETIME
, @ToDate DATETIME

SELECT @FromDate = '2008-02-09 00:00:00.000'
SELECT @ToDate = '2008-02-09 01:00:00.000'

SELECT AVG(DATEDIFF(ss, B.SomeDate, C.SomeDate))
FROM A WITH(NOLOCK)
INNER JOIN B WITH(NOLOCK) ON A.BID = B.BID
INNER JOIN C WITH(NOLOCK) ON A.CID = C.CID
WHERE A.SomeDate>=@FromDate AND A.SomeDate<@ToDate
AND DATEDIFF(ss, B.SomeDate, C.SomeDate)<100000


Any ideas?

-a