I just did a fresh install of ubuntu 6.10 not 64 edition,(ASUS A8V-VM SE Motherboard socket 939 with an AMD Athlon 64 (2.2 ghz processor) and 1 GIG of Ram) It has an integrated nic card (VIA RHINE? I believe) and an encore ENLWI-SG wireless PCI card as well as a nvidia 7300GS PCIe card (onboard VIA video disabled in BIOS). I used envy to configure my video and I was able to use network manager to get my wired and wireless working. I then upgraded to 7.04 . I re ran envy to make sure the drivers worked ( I think I read that somewhere?) Anyway everything works fine, however if I leave the pc idle for a while (roughly 10 min, long enough for my screen saver to activate) my wired network connection stops working. if I enable wireless I can again connect to the internet however if I disable wireless and switch back to wired I still cannot connect, a physical reboot is required to get my wired connection working again. I am currently using DHCP and I believe my router is set for a long DHCP lease time (Buffalo WHR-G54S flashed with DD-WRT) Other than LSPCI is there any commands that I may need to check to see what may be up? I am still very new to Ubuntu and linux for that matter.(sorry if I was a bit long winded, I though more hardware specs would be helpful)
Thanks for any help in advance.

I'm no Ubuntu user but....

it sounds like the system is going into suspend mode
check your power settings
I had a similar problem on a Suse installation everytime I closed the lid on my laptop I changed 'on lid close' to activate screensaver and all worked fine after that

however it's a desktop PC and I have all disabled all the power management that I can locate, I did however semi-solve the issue, I put a pro100 in and have not had any disconnect issues since..really strange.