Time estimate changes when clicking at "non-working days" viewing chart board

Steps to reproduce:

1. Go to "Agile" -> "Chart Board" -> "Burndown"
2. Click at "Toggle Visibility" to see versions
3. Click at the configuration "wheel"
4. Notice the "Time estimate", "Time spent" and "Time Remaining" values (wrong values).
5. Click "Non-Working Days", don't modify anything and close.
6. See that the time estimates has changed, actually, to the correct values.

I was able to reproduce this issue with customer's XML backup, across different projects and combinations of versions, burndown charts.

This issue came up at EHSP-9867 support ticket, backup, logs and screenshots avaible.

The only thing I could catch in the logs is:

2010-09-16 17:38:46,750 http-8080-3 WARN xxxx 1058x215x2 193qbj7 127.0.0.1 /secure/CCBRefreshBoard.jspa [greenhopper.service.charts.DefaultHourBurndownChartService] Failed to compute remaining estimate for sprint start with planning and work log on the same day: ALERTS-772, 2010-08-30T00:00:00.000-03:00