Hello,
You can try using our advanced automation product, Automation Anywhere Premier/Enterprise version. Using MWC (Manage Windows Control) command you can get the status bar text (of mozilla browser) in a variable and then loop until the variable includes 'Done'. That way, you can pause the task until the webpage is loaded fully.
You can download free version of Automation Anywhere 5.0 from our website:
Automation Anywhere - The Leading Automation Software
Hope that helps.