Anyone who is a site collection admin is able to edit the site page using 'Edit this page' option. The user who is having issues editing the page has full acccess, minus the ability to set permissions (custom role I created a year ago). She had no problem editing the page in the past, but now she gets the error message below. This just started today. The last update on the farm was 3 months ago when I updated it to SP1. Since then there hasn't been any Windows or SP updates. I have since given her full permissions (using the buit-in role) as a test, but the same error is still occuring.
Sys.WebForms.PageRequestManagerParserErrorException: Attempted to perform an unauthorized operation