Why is this 777 with doors and windows covered?
The aircraft is in storage. The Boeing 777-212(ER) seems to operated by Singapore Airlines under lease from Pembroke before being withdrawn from use in Dec 2014. After that, the aircraft is under storage at Southern California Logistics Airport.

The windows are covered in aluminium foil for storage; however, the engines appear to be still there (which will usually be removed), which indicates that the storage was planned for only a short time.