Well, it can be done but 2007 was SharePoint Workflow V1 and has a lot of issues. The workflow is quite limited. V2 was 2010 and things are much improved, but it's stil lan area where everyone is having issues. Personally, we do most workflow in the InfoPath form using rules, conditional logic and view switching. The nice thing about doing workflow in the form is that the user sees the status right in the form without any hookup. This probably handles 90% of all workflow needs. Of course, Microsoft doesn't push Forms-based workflow because it doesn't sell more copies of MOSS and that's fair. Forms-based workflow is easy to do, more integrated into the form, but you can't easily copy them and since the workflow metadata is in the form you have to take extra steps to hide it if it is sensitive (but that can be done).
Sorry I didn't answer your question. To debug SharePoint workflow I'd start by looking at hte SharePoint logs. Then, recreate it and see if it works the second time.