For me the computer is not the problem.
Flash Catalyst, is used to generate GUI with spark library then, i don't thik that the problem is that you've got MX and Spark component.
If you can't go to the design vue it's probably to an error on the source code (forgot a < or a >...)
To solve your problem, I suggest you to copy your project and delete all component of your GUI.
Then, redraw component one by one (from your copy of the project) and switch to the design view to solve your problem.
I hope you have helped...
I've also encountered problems with design view when I worked with 4.5 inside Flash Builder 4.
There was no syntax error and the code compiled perfectly, but the design view wasnt working.
I've also had some issues. Occasionally, it works after I delete the .metadata folder in the root but that means you lose all your FB settings. Maybe make a copy of the the entire directory, then delete the .metadata folder and see if that helps. If not, restore.
Syntax is right and application works perfectly
But the problem is design view, where i am not able to do visual changes.
Flex SDK teams should put some light on it
I have the very same issue. After importing n existing project from flex builder 3 (using the flex 3.3 sdk) into flash builder using 4.5 sdk i just see a grey screen in the design view?
Can anyone shed some light on this issue please?
And what else would any of you expect from a half-baked beta product that is masquerading as the real production-ready thing :?)
This is nuts I have 2 redesign the entire front end of my project just to use one of the new components. Thats thousands of lines of code that will take weeks to complete! Absolutly crazy!
And what are you going to do when they change it between Beta and Production and when they arrogantly state that it was just that, a Beta ;?)
I for one am the most peeved by the fact that they dress it all up with press releases, as if it was a production-ready product, but officially support it as if it was dirtier than dirt :!(