Hi Adam,

sorry to hear you're having problems with this.

Can you please try a few things:
1 - make sure that the SH404SEF plugin is above the MT plugin in the list of system plugins (i.e. a lower order number, making it appear higher on the list)
2 - turn on maximum error reporting in the Global Configuration. That's to try to get the blank screen to give you some more of an error message
3 - turn on the system debug plugin
4 - just in case it's an "out of memory" error can you perhaps increase the PHP memory limit?
5 - check the apache error logs in case there's anything reported in there
6 - try disabling any other plugins and modules that would be operational on the page that's giving you the blank screen. This would include any "content" plugins, not just system ones.

There have been a couple of other people reporting blank screen issues, but I just haven't got to the bottom of it yet. I thought that CommunityBuilder was a common factor, but it isn't in your case. I would really like to find out what's going on.

Best regards,
Stephen