Plug and Play Error with Ethernet Card

Hi,

I have a Dimension 4500S with dsl wlan router and today I tried installing a new graphics card and its driver (GeForce 6200, PCI, low profile). I didn't manage this and even got a second problem.

After inserting the card and changing onboard to auto in Bios I couldn't load the driver, screen went dark, cursor blinking in the left upper corner.

After deinstalling the driver (control panel, software) and disabling the antivirus-tool (could have been the reason) i tried a second time, but same failure.

Third attempt brought an additional problem. After restarting the computer I got a "Plug and Play Configuration Error". I went to Bios, found nothing wrong and continued. After appearing the desktop I realized the ethernet card is off and no connection to internet. Properties in device manager say I should disable any other hardware and no resources for the ethernet card.

Obviously the pc doesn't recognize the ethernet card.

Restarting again brought same plug and play problem.

How can I solve this plug and play problem (and afterward the graphics card matter)? I didn't touch the ethernet card while inserting the new grahics card, ethernet cable is plugged well. Two days ago I installed Service pack 2, but without any troubles.

Thanks foruseful hints,

Freeman12