Two month old Gateway DX4300-03 randomly shuts down when on the internet.

I have the same pc my power supply went bad after 2 weeks.Pack up the pc and return it ASAP I have nothing but problems with mine.Gateway use to make good pcs, those days are gone,mine was a gift and I had to keep it.

I had the same issue with a Gateway DX4300-9 desktop. The computer appeared to halt after a few minutes. Monitor would go black and no hard drive activity. I went to the BIOS and changed two settings:
1. Like an article on Vista Forum stated - changed video to Onboard - was set to PCIE
2. Another setting to Halt on "All errors - but Keybord" was set. Changed to "No Errors".

It seems to be working fine now.

It is under warranty. Call Gateway, as you may need to have it replaced if the computer is just powering off. That is normally a sign it is overheating. You paid for this warranty so avail yourself of this service.

Replace the power supply with a 500-600 watt.