Could you please post the contents of the SQL Backup log for the restore process that failed?
The default folder where the logs are stored is C:\Documents and Settings\All Users\Application Data\Red Gate\SQL Backup\Log\<instance name> on Windows 2003 and older, and C:\ProgramData\Red Gate\SQL Backup\Log\<instance name> on Windows Vista and newer.
The default folder where the logs are stored is C:\Documents and Settings\All Users\Application Data\Red Gate\SQL Backup\Log\<instance name> on Windows 2003 and older, and C:\ProgramData\Red Gate\SQL Backup\Log\<instance name> on Windows Vista and newer.