Expedition PCB- .Lyt file error

lyt file

Hello Friends,

I am working as a PCB Designer with EXPEDITION PCB.
I have some clarification about PCB File.
I had done one 4 Layer PCB few month ago. while that time i opened the pcb. its opened. Recently i have try to open. But i couldn't open. there is appear error message. The message is:
Unable to load design\...\PCB\work\Layout_temp\ Layout DB.Lyt) The file with the '.lyt' extension is not a Layout partition.
like this appeared. so i couldn't open. anybody can help me to solve and explain about this problem.
What is The Layout_temp file?some pcb file only contain the Layout_Temp inside the 'work' folder.
in Some files there is no Layout_temp inside the 'work' folder.
Herewith i have attached the image capture file of error appear.

If anybody knowing about this, kindly give your solution and clear expalination.

Thanks & Regards,
Sankar.[/img]