I'm going to repost my response from another thread about the same issue:
Good Morning,
We released Desktop Collage yesterday afternoon, however despite internal testing and everything working A-OK on all of our internal machines, some users who purchased the dream were unable to run it on their own systems. Since this was late in the evening when complaints started coming in, we pulled the dream off the website to prevent more unhappy customers from downloading and attempting to run it.
Currently we are trying to reproduce the issues users were having (not switching to the dream, a black screen only etec.) and get a fix in place for it before we repost it.
Like was said on the thread before the dream was removed, we had not seen the problem previously in our testing. I personally have been running the dream for over a week now, have switched back and forth between dreams (I test all the dreams that users submit to the site before posting them) and even went through the full activation process yesterday before posting the file to the site.
We are looking into what happened and are going to get a fixed version out as soon as we possibly can.
My apologies for the confusion and inconvenience,
-Mike