You are not alone, Adobe has been criticized severely right from the beginning about its installers, but Adobe just do not care enough to fix anything.
Here is a work-around solution that could help you:
I hope this helps!
PS: the CS5 is due on April next year
Hard to tell. Using the clean script as advised in the linked thread may help. other than that, a look at the install logs might reveal something...
Can you please give me the link of your blog again. Thank you!