Jaff,
We return this error message when the time needed to create a PDF exceeds ~40 seconds. This limit is applied to both free and paid accounts.
Typical reasons for this error are:
- Complex or long running JavaScript code
- The page you want to convert resides on a server with slow downlink speed
If you let us know the URL of the page that fails to convert, we can look into the problem - either post the URL here or if it is sensitive you can send it to support@pdfcrowd.com.