Desktop Hangs on Standby

Hi, I have never tried posting here before, but I'm not sure what to do about this problem and I was hoping somebody could help shed some light on the subject. This happens occasionally (maybe 1 in 4 times) when the system goes into standby mode when inactive.

The computer appears to stand by and the case fans/LED's all go off, but the LED's on the USB keyboard and mouse stay on. When I try to wake the computer from standby, the keyboard/mouse will not wake it. In fact, the reset and power button also have no effect. The only way I am able to boot the system is to unplug the power or shut off the power supply for 5-10 seconds, then turn it on. From what I have read, the answers seem to be that I should just fully disable the standby/hibernate mode since it is a desktop, but what I want to know is whether there is a hardware problem that I could possibly fix with an RMA. I just built this computer a couple weeks ago, so I still have time on warranties to get a replacement part if something is bad.

I am using Vista 64 bit with a Gigabyte GA-MA790X-UD4P motherboard, XFX Radeon HD 4890 graphics, and 8 GB Crucial DDR2 1066 SDRAM if any of that is relevant to the discussion.

Thanks.