Hi Ken,

 

Thanks for responding - I've been playing around reconstructing my page last night/this morning and think I've found my problem.

 

The modal popup panel was enclosed within an Ajax Update panel and the error was occurring when the panel was updating - removing the update panel seems to have fixed the problem (and made CE work a lot faster!!).

 

I'll do a bit more testing - but certainly looks like my problems have all gone now and will almost definately be purchasing CE - great product!

 

thanks