Utilize a globall change to update the date on the employee in question:

1. In Payroll > Administration > Globally change records > New Employee Change
2. Under the available fields, expand Employee Event
*Depending on where the incorrect date appears, that would determine your next steps
For example:
Select scheduled date and an operation of replace - Replace [incorrect date] with (desired date)
OR
Select Actual date and an operation of replace - Replace [incorrect date] with (desired date)
OR
Select both if both are incorrect
3. On the filters tab, Filter on the specific employee record
4. Click preview change and ensure that the correct Event is showing
5. Click change now
6. Attempt to open the employee again