Enable for Widgets- Fatal error

i want to enable the plugin in the widget area but it gives me this message:

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 40961 bytes) in /var/www/virtual/fagform.is/htdocs/wp-content/plugins/simple-lightbox/model.php on line 947

i’ve tried:
finding the problem in model.php (not good at finding code)
disabling lightbox in other places (Home page,Posts,Archive Pages )
disabling and deleting plugins
different options in lightbox

i know this plugin is only beta, but i was wondering:
is it just my site or do others have this problem to?
should i keep it disabled for now or is it easy to fix?

appreciate if someone would reply

http://wordpress.org/extend/plugins/simple-lightbox/