See http://www.fmsinc.com/MicrosoftAcces...ons/index.html
The code should not be the cause of the error. Don't know what you did/how you tried to change the combo box to a text box.
Close all forms.
Open the subform in design view
One method is to:
Select the combo box.
Right click on the combo box, select "Change to", then select "Text Box".
Close and save the sub form.
Another method:
Delete the combo box
Re-add the "User_ID" field (text box control) to the form.
Close and save the sub form.
Open the main form. You will (should) see
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I missed a reserved word - "Password" (in table tbl_Users) is also a reserved word .... I would use "UserPW" or "UserPassword".