Workflow works intermittently

Hi All,

We have set up a simple workflow: when a new lead is created, automatically create 3 tasks (2 week follow up, Final follow and a reminder for this lead to manually be added to mail-chimp). The leads can be added manually but most of the time they come via our company website when they download product evaluation.
The workflow always works when when we add a lead manually but with the website leads, it is hit and miss. It works well for a few days, then there is a break for a few days… We seem to have tried various options on the workflow. Please can you help? Any ideas?