We had configured a publishing site's Pages library to make use of the built-in approval workflow. However, we noticed that when users submits a page in the library for approval the workflow fails with the message 'Error Encountered'. There were no other messages provided by SharePoint explaining as to why an error occurred (and even the workflow history option yielded nothing).
We then went into the workflow settings and started examining all the fields. We noticed that the 'Approvers' field was set to a group called 'Cars & Trucks Owners' where as the actual name is 'Cars & Trucks Owners'. As soon as we changed the name (by replacing '&' with '&') the workflow's started functioning smoothly. It seems that SharePoint uses the ';' as a delimiter and was looking fro two groups (i.e 'Cars &' and 'Truck Owners') to assign the workflow task to. Since these groups didn't exist it started erroring out.