oops wrong button..
Okay, so your using Windows Live Writer and you're trying to detect/apply your theme from your blog and every time you try to, your getting this script error '...running slow; do you want to continue' from Adobe Flash right?
Since the same error keeps coming up, In my opinion... I think you need to go in, find out what's using Adobe Flash and disable it from your blog [possibly a plug-in]. It would seem to be something on the site/theme that is using Adobe Flash, and it's not working well when you are trying to apply it to a downloaded theme.
Try that...
Hope this helps.