You can look for help on:
- http://ubuntuforums.org/newthread.php?do=newthread&f=326 (add [wubi] prefix)
Of those I'd recommend ubuntuforums for help if you're not sure what the problem is. Askubuntu is good if you know what the issue is, either searching for an existing question with an answers, or asking a new one. I don't think there is a dedicated Wubi support person on Launchpad anymore... but there are a number of questions/answers there that you can review.
Any support requests in the blog comments will likely be ignored - and those containing wubi log files will be deleted.
My advice is... if you are having problems with Wubi then it might be less effort to try a normal dual boot or run it off a live USB: Wubi is designed to try out Ubuntu easily, and if it doesn't work then it's questionable how much benefit it would be to spend hours troubleshooting it. In addition, a lot of community members don't use it (and/or Windows) so you are more likely to be told just not to use it.