lofty, there is something conflicting with your install then because I have a huge project in Dreamweaver and it runs fine. are you using any MX add-ons or behaviours downloaded from their site? some of those could be buggy, but the base install of DWMX is fine.
I won't expect an answer to this, but food for thought. Legal Copy of DW and not Cracked?
Try emailing their support. I've had very good results and experiences with their support. Also, their forums might be of help since a lot of the Macromedia Devs read the questions and reply to them, also answering questions like "why isn't this in DMX?" or "Will this be in the next update of DMX?". Their forums aren't as lively as these and you often have to wait longer before you get an answer, but it might just help you locate the problem.
I don't think theres anything wrong lofty, personally I've had similar problems and know tens of machines at work which have it crash regularly too. As you said its a Java app and for starters thats going to make it much more resource hungry than something written in a more "pure" language
I just started using MX and I really think it is very powerfull. I grafted right on to my existing sites and SQL Server 2000 db's with no problem. I have a Live Preview extension which works on the host usinng the remote db and saves a step from having to upload and view in the browser. I am very thrilled to create code more rapidly and never have been a fan of WYSIWYG until now. I think the biggest drawback is that there is so much to learn to master the program and you really need to try things to understand how it works and develops code. The extensions (which are developer addons) appear very useful and add very useful tools to the code process.
I found that it creates some ASP script pages and variables when it creates code that assign values such as connection strings to variables that are different than what we use here. Does anyone know if this is modifiable in the software or have created a trick around this? I am thinking of just editing the files in the connections folder but if I can control this from within the program it would be more useful.