How about the Video Card... Sometimes VC can heat up and over heat the system as well.

Also, how about the CMOS, resetting JP1?? (If all else fails)

Hmmm... have you tried rebooting with the TV Tuner Disc in the Drive?? It might be possible that it knows what it's looking for but it cant find the file (looking in the drive)... if that doen't...

The reset button is prob. in the botton, near the battery. Can you try to boot up in safe mode. Then check the compatability with the TV tuner and your harware versions. Maybe you might need to...

If you already changed the PS, try the fans (heatsink, case fan, etc.) make sure no cards are over heating.

1) could be the ram not letting boot into the BIOS, if you don't hear a beep, it's the ram
2) if the fans don't run, it's the power supply
3) double check the jumpers, make sure J1 is accurate,...

You can order the CD fro Dell, you need your serial number... OR, under programs, you'll have the Dell icons, and you can reset settings there.

boot up under safe mode (press F11 or F10 when booting, can't remember) then try running a spy ware check and virus scan, also try a defrag on disk. Sometime, cleaning out all unnecessary junk in...

Open your case and assure the the CPU fan is running properly....this sounds like the CPU is burning up and shuts off. If that is not the case, then is will be the power supply.

OK... sorry I wasn't online, I travel a lot, and I just to into my office in Roswell, NM.

1) network card and 2)ethernet adapter are the same thing. Try some generic drivers from Microsoft.
...

Most windows installations allow you to work off of generic drivers.
My suggestions is to load those first.. from the device manager. Then, once online, sony sites can provide you with drivers based...