Hi noteperf.
First go via FTP to the folder of this plugin an rename the folder.
After that the plugin is deactivated and everything should work as before.
The error – I don’t know it exactly – could be a problem of less PHP-Space. So take a look here: WordPress Codex.
If you can’t get into your admin dashboard, try resetting the plugins folder by FTP or PhpMyAdmin (read http://codex.ww.wp.xz.cn/FAQ_Troubleshooting#How_to_deactivate_all_plugins_when_not_able_to_access_the_administrative_menus.3F if you need help.
Then check the memory limit for your site. There are a number of ways to increase it, depending on your host and server settings. Do a search on these forums for “increase memory limit” and you should find everything you need.
Thanks for the replies, they helped a lot – everything is now back to normal! 🙂