I also have the exact same problem using a RTL8169sc/8110sc on an Asus A7V-333X mainboard and first noticed this with 2.6.32.11-99.fc12.i686.PAE. I tried updating with updates-testing enabled which resulted in 2.6.32.12-114.fc12.i686.PAE being installed, but I see no improvement. I haven't reviewed the changelog to see if that should be expected or not.
I also have the exact same problem using a RTL8169sc/8110sc on an Asus A7V-333X mainboard and first noticed this with 2.6.32. 11-99.fc12. i686.PAE. I tried updating with updates-testing enabled which resulted in 2.6.32. 12-114. fc12.i686. PAE being installed, but I see no improvement. I haven't reviewed the changelog to see if that should be expected or not.