PCI bus 4, device 2, function 0

Go from the Start menu to Control panel>Device Manager, find taht device in the list and right click it. Select Properties then click the Details tab. Scroll to HardwareIDs and take a note of the four characters which follow VEN and DEV.

Go to http://www.pcidatabase.com and insert the DEV reference in the appropriate box and click search. Select the VENdor from the list provided and click on it. Click the browser's Edit menu then Find and enter the DEV in the box to save scrolling through the entire page. When you find the entry, there should be a link to tghe manufacturer's website for a safe and free download.
 
PCI Simple Communications Controller

PCI\VEN_8086&DEV_1040&SUBSYS_10008086&REV_00
PCI\VEN_8086&DEV_1040&SUBSYS_10008086
PCI\VEN_8086&DEV_1040&CC_078000
PCI\VEN_8086&DEV_1040&CC_0780

 
The drivers for this device are not installed. (Code 28)

There is no driver selected for the device information set or element.


To find a driver for this device, click Update Driver.
 
There's no trustworthy driver availlable for that device which is only a Fax MODEM device. Do you really want to send faxes? If not, don't bother with it and stop the nagging message by disabling the device.

Is your PC made by a large manufacturer - Dell, HP perhaps? If so, which maker and model reference.