Dashboard fatal error

Since few days in the Dasboard page, the “WordPress Blog” and the “Plugin” boxes show the following error:
Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 1966080 bytes) in /web/htdocs/www.XXXXXX.com/home/wp-includes/SimplePie/Item.php on line 2736
but everything else works fine.

Any idea how to fix this?
TIA