Amortize Adjustment

We are in a process of converting our books as per IFRS standards and in doing so have created a tax book and have componentized assets in the corporate book. We have found out that in a few assets somehow the 'Amortize Adjustment' check box under books --> depreciation screen got checked and the Amortization Start Date is showing as 31-Dec-2009. We did not wanted this as we wanted the amortization to re-calculate from the begining of the asset placed in service date.

Now the system is not allowing to un-check the box or change the date. Is there a way to do this.