XIRR fail -- cash flows alternate between positive and negative

Hi - I'm having a hard time determining the IRR on a project with cashflows that are sometimes positive (+) and sometimes negative (-). I understand this is a limitation of the XIRR formula (through google searches), but I can't find a proper alternative to the XIRR formula.
My challenge is to find the IRR for these irregular and alternating (+/-) cash flows.
The attached sample workbook shows my problem.
Thanks in advance for any help!
Jeff