PCI serial port Dell Optiplex 755 Windows 7

Error

1. First
Run windows Updates

2. Second
Install the followings:

Download the followings:
http://www.dell.com/support/drivers/us/en/04/DriverDetails/DriverFileFormats?DriverId=R255437&FileId=2731111318

http://www.dell.com/support/drivers/us/en/04/DriverDetails/DriverFileFormats?DriverId=R255438&FileId=2731111319

http://www.dell.com/support/drivers/us/en/04/DriverDetails/DriverFileFormats?c=us&l=en&s=bsd&cs=04&DriverId=R229705