In the SalesLogix web client the insert Account Contact screen behaves differently than the LAN version in that you can modify the Account level fields when you select an existing Account to use.  I was recently asked how to make it work like the LAN client so that the Account fields are not editable.

When I looked at the form (which is a custom Contact smart part called InsertContact.aspx) I noticed that on the Account lookup control there is code in there to do this, however it does not appear to work correctly.  In the code you can see it has something like this:

if ((account != null) && (contact != null))
    {
        txtContactAccountName.Enabled = false;
        adrAccountAddress.Enabled = false;
        phnAccountMainPhone.Enabled = false;
        phnAccountFax.Enabled = false;
        pklAccountType.Enabled = false;
        pklAccountSubType.Enabled = false;
        pklAccountStatus.Enabled = false;
        pklAccountIndustry.Enabled = false;
        txtAccountBusinessDescription.Enabled = false;
        usrAccountManager.Enabled = false;
        ownAccountOwner.Enabled = false;

I found that by changing it to read like this instead, it worked:

if ((account != null) && (contact != null))
{   
    txtContactAccountName.ReadOnly = true;
    adrAccountAddress.ReadOnly = true;
    phnAccountMainPhone.ReadOnly = true;
    phnAccountFax.ReadOnly = true;
    pklAccountType.ReadOnly = true;
    pklAccountSubType.ReadOnly = true;
    pklAccountStatus.ReadOnly = true;
    pklAccountIndustry.ReadOnly = true;
    txtAccountBusinessDescription.ReadOnly = true;
    usrAccountManager.ReadOnly = true;
    ownAccountOwner.ReadOnly = true;

Go figure.  I guess the enable property is not quite functional.