To temporarily solve the problem, I've turned off all but two other plugins, which leaves the Checkout working but other parts of the site down or just plain odd-looking.
Is anyone aware of specific conflicts between Checkout and other plugins - or a combination thereof? Or another reason for this problem? I've looked unto prioritizing the different Scripts, but didn't want to get into that without checking here first.
The plugins that she has installed, and that were active until recently, are:
- Contact Form 7
- Flickr Manager
- jQuery Updater
- NextGEN Gallery
- Spam Free WordPress
- Stout Google Calendar
- TinyMCE Advanced
- WordPress Google Calendar
- WordPress Importer
- WP Super Cache
I know, I know - a lot of plugins, but the site uses them. The ones in italics are still active.
Thank you in advance for your help - we really appreciate it!