Ethernet Adapter not recognized

So I have a Dell PC I bought a little over 1.5 yrs ago that came with an integrated ethernet adapter on mobo.
worked fine uptill november last year when it started giving me problems where the comp would not recognize the adapter on start-up, a reboot would solve the problem and I'd be able to go online. recently even that stopped and I can not go online, neither would it recognize the adapter on the system device list at all.

Thinking that the port has gone bad, I bought a new PCI Express X1 card and installed that on the computer.
It showed up on the device manager list only the very first time I started the machine, on every subsequent start-up, the device manager list does not show either of the adapters and I have not been able to go online on that machine for more than three weeks now.

any help on this would be great if somebody has gone thru similar predicament.
thx

vostro 460
service tag# CR6M0R1
the PCIe card is a TP-Link TG-3468, it did come with the install disk
thx in advance

thx for the reply
I've tried both these steps already in the BIOS, disabled the adapter and then restarted the comp, no change, reactivated it in the BIOS and after the re-start, no change.
After this, I took the new PCIe card out, shut the comp down, installed it again, restarted the comp, same problem persisted, neither adapters show up on device manager, the light does come on on the new PCIe card but the comp does not recognize it
would a re-flash of the BIOS make this work?
thx in advance for the help

tdcv said:

thx for the reply
I've tried both these steps already in the BIOS, disabled the adapter and then restarted the comp, no change, reactivated it in the BIOS and after the re-start, no change.
After this, I took the new PCIe card out, shut the comp down, installed it again, restarted the comp, same problem persisted, neither adapters show up on device manager, the light does come on on the new PCIe card but the comp does not recognize it
would a re-flash of the BIOS make this work?
thx in advance for the help

It may help to try clearing the cmos then setting BIOS to defaults.

I did that as well, to no avail unfortunately
could this be a virus problem?

First open up the PC. Disconnect the adpater. If you have any dust remover spray, spray the pci port and the card. Plug it back in and test. If its still not working do you have access to another PC to test the card in?

The PCIe card is brand new, will test on another comp
it's just so frustrating cause the comp is practically new, sucks for me

Yeah it does suck I have gotten new components that are defective before. This is the easiest way to test it.