Fatal error message for class-pclzip.php

Hi,

the last couple of days, I’ve recieved an error message on my own wordpress site – not all the time, but on and off:

Fatal error: Maximum execution time of 30 seconds exceeded in /var/www/bjerreandersen.dk/public_html/wp-admin/includes/class-pclzip.php on line 2574

At the same, I can’t enter the admin-page…the login-page is just blank.

The error is apparently not connected to any upgrade og plugin-installation, as the site ran well for a while after last time I installed a plugin…

Is there any quick solution? Would it help to overwrite the class-pclzip.php file with a new version etc.?

please help 🙂