Crash on NextGen Gallary Plugin

Hi There,

I am completing a website for my wife and everything was running fine until I tried to activate the NextGen Gallery plug-in. I now cant access the back-end to make any changes to the website as this error keeps coming up.

If anyone can assist, that will be greatly appreciated.

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 122880 bytes) in /home10/mphairan/public_html/wp-admin/includes/class-wp-upgrader.php on line 1476