It meas that in your password.tpl file you have a syntax error in line 52. I had the same error and when I checked the file in line 52, I found this:
<p class="clear">
<a class="button fr" href="{$link->getPageLink('authentication', true)}" title="[spam-filter]l s='Return to Login'}" rel="nofollow">{l s='Back to Login'}</a>
</p>
There should only be one {, so i fixed it like this:
<p class="clear">
<a class="button fr" href="{$link->getPageLink('authentication', true)}" title="{l s='Return to Login'}" rel="nofollow">{l s='Back to Login'}</a>
</p>
And it worked.