PS – I have tried sending the same message to only one person, and it gets there fine. 

and latest version of sp core and plugins?

does it happen here too?  asking because we havent seen that yet, but certainly possible we havent attempted it…  please send one to me, andy and yourself…

My version is a few days old.  I’ll try sending the exact message (so it won’t make any sense to you), but I think it might be a quote or slash causing the problem…

I received the message just fine and intact…  did you get it too?

If so, please update your site and see if still an issue…

I updated my version and still having troubles.  Most of the people I sent the PM to were unable to open it.  I recieved a few replies to my PM that I was also unable to open (the message box tried to load, but then never did).  I’ll just use Mailchimp for large mailings, but thought you might want to know there’s something strange going on…

so far, its constrained to your install only – no other such reports, so more data is required…  still, would like to know whats going on because with wider distribution, could happen to more than just you…  assume you update, did sp core, plugins and themes (though the latter probably doesnt matter)?

can you provide any more data??  any errors in server logs?  and errors with firefox and firebug in the console? is it browser specific?  which browser(s) does it occur in? etc…