Have recently upgraded to Magento 18.104.22.168 and now when you go through checkout and enter your details and password, it popups with an error saying - Please make sure passwords match.
I have tried over and over again and cannot get it working.
also try this
Change this code
app\code\core\Mage\Customer\Model\Customer.php $confirmation = $this->getPasswordConfirmation();
to this code
$confirmation = $this->getConfirmation();
it's because of this change in 1.9.1 update. You have to update your extensions code -Customer passwords are no longer stored in clear text during registration.
I would suggest to check if these exist as attributes.
Under Catalog->Attributes->Manage Attributes check if they exist as attributes called Storeowner or Storetype.
Then you will need to either remove them if applicable or just set them to not required under Properties->Values Required = No.
If like @cruzier your "my account" still doesnt work after the above changes make sure you either disable compilation or re-compile in admin under system|tools|compilation.