PS3 Networking issues... PS3 itself?

[Uniquely]

I've had my PS3 for almost a year now I think. I've had networking issues with it the entire time. My issues are....

1. Near constant DLNA errors while streaming media. It never actually stops the streaming.... but the little error message pops up in the top right corner every minute or two. It's just plain annoying and eliminates my PS3 from use as a streamer

2. Random sign outs from the Playstation network caused by DNS error. This is less frequent... about once an hour I'd guess. This has been a HUGE reason my PS3 doesn't get more gaming love. I'm a multiplayer kind of gal... so it would drive me NUTS to get randomly signed out of matches.

Here's what I have tried...

I've used two different routers during this time... a Belkin N1 Vision and a Linksys WRT54G version 5.

I've tried using both a wired ethernet connection from router to PS3, and a wireless connection.

I've set a static IP for the PS3 and entered all network settings manually.

I've tried turning off UPnP in the router.

I've placed the IP address for my PS3 in the DMZ zone of my router.

I have a PC and two 360's that connect to my network via ethernet; and a PS3, Wii, Lexmark printer, laptop and iPhone that connect to my network wirelessly. My PS3 is the only thing on my network that has issues... and these issues have been constant despite all the steps listed above.

I'm no IT professional... but I'm not a networking virgin either. I've tried everything I know and could research on the net.... and nothing fixes it. I truly believe it is the PS3 iself.... either a bad networking card or a bug in the networking software.

Any thoughts on what to do next?