I recently downgraded a Lenovo Thinkcentre M90P from Windows 7 to Windows XP Pro, I've Installed from a my Win XP CD no branded (an original CD with no brand drivers included).
The Machine's chipset is: Intel 5 Series/3400 Series
Now from Device manager I've found 2 unknown devices, or better 2 devices without drivers:
PCI Simple Communications Driver
PCI Serial Port Driver
I've downloaded from Lenovo's site all drivers for this machine but it seems there aren't drivers for these 2 above.
I' ve read in another forum that for a Lenovo M57 or M58 the same problem was solved installing Intel AMT, but for this machine/motherboard I havent found this kind of drivers.
What kind of device could be? Is there someone that had the same problem and has solved it?
I understand that you are looking for driver for your OEM system.
Unfortunately the drivers that you are looking for will not be provided by Intel(R). You are missing the chipset driver and AMT.
From our side you may try to run the Intel(R) driver update utility to check if you can find a generic driver that may work.