I have the following VF page that is called by a button on a Person Account record.

<apex:page standardController="Account" title="Cancel Account">
    <apex:sectionHeader title="Cancel Account"/>
    <apex:form id="theForm">
        <apex:pageBlock id="theBlock">
            <apex:pageBlockSection id="sectionOne">
                <apex:outputField value="{!Account.Name}" />
                <!-- Bound to Date Field -->                
                <apex:inputField value="{!Account.Account_Cancel_Eff_Date__c}" />
                <!-- Bound to Picklist -->
                <apex:inputField value="{!Account.Account_Cancel_Reason__c}" />
            </apex:pageBlockSection>
        </apex:pageBlock>
    </apex:form>
</apex:page>

When the page is called for a person account, Salesforce returns:

Validation Errors While Saving Record(s)

There were custom validation error(s) encountered while saving the affected record(s). The first validation error encountered was "Record Type ID: value not valid for the entity: Account". 

When the page is called for a normal Account, it renders as expected. If I remove the inputField that is bound to the picklist, then call the page for a person account, everything works as expected. What's going on here?