Network locking up

[Todd Simi]

Hi,

I am finding that I wave to run 'service network restart' every
couple of minutes when downloading most anything.  Once I do, 
the downloads usually continue as usual.  I seem to have picked 
this problem up when I upgraded to FC5 from FC4 and changed motherboards,
so I don;t know which caused it.

Mobo is  ASUS P5WD2-E Premium w/Pentium D (830)
Net      OnBoard Marvell Gigabit

Any ideas if I might just have something setup poorly?
What to check?

Thanks
Todd