As pointed out by Jerry and Ron, if I include a guess in the XIRR, then I
get the expected result.
But, in the general case, there is no way for a user to know what to guess.

Excel 2003's Help states:

"In most cases you do not need to provide guess for the XIRR calculation. If
omitted, guess is assumed to be 0.1 (10 percent)."

If I use a guess of -.1, I get the expected result.

What do folkes think about using the following as a guess:

=XIRR(B3:B44, A3:A44, SIGN(SUM(B3:B44)) * .1)