After upgrading the SelfReg-module from 1.10.1 to 1.11.1 I discoverd some strang
behaviour of the signup-form.
When I leave a required field blank and submit the signup-form, I will see an
error-message for the required field.
Then I fill in a value in that required field and submit the form again.
The signup-form shows up again with the same error-message and no value in the
required field.

I have looked at the code (action.signup) and think that it is caused by the new
hidden and encrypted data-field.
That field stores all the old values there where posted at the first time.
Changed fieldvalues will not be stored in the data-field.

I uninstalled version 1.11.1 and again installed 1.10.1 that worked well.