Fatal error: Allowed memory size of x bytes exhausted in contemplate.module on line 777

Same to me when I try to modify a content template :-(
How did you solved? (did you solved?)

same to me :(

It seems to be a recursive variable problem from CCK.
I (temporary) solved by changing contemplate/contemplate.module ~ line 709:
from
if ($depth >= variable_get('contemplate_max_recursion_depth', 10)) {
to
if ($depth >= variable_get('contemplate_max_recursion_depth', 1)) {

I strongly reccommend using the tpl way to modify the design; you can put a
node--contentype.tpl.php in the theme tpl directory and modify directly the file.

<3

there is no delete

Another way to temporarily get around the issue is to go to /admin/config/contemplate and set "Max recursion depth" to 0.