Boot problem with Fedora on R500

[Ummon]

Hi

I´m a new Thinkpad R500 user and wanted to use Fedora in a dual-boot setup together with winXP.
Unfortunately, when trying to install Fedora, everything goes well until my first boot attempt - there I get the error

PXE-EC8: !PXE structure was not found in UNDI driver code segment.

Strangely, this only happens with Fedora (11,12,13) - opensuse does not have this problem and works flawlessly. Googling the error did not really help. Would be very glad if someone could point me in the right direction, since I want/need to use Fedora-specific software.