USB ports randomly shut off

[ElementX]

I have a custom built PC with an MSI X38 Platinum MB.  It has worked great for the past 4 years up until recently.  Lately my USB ports shut off randomly while I'm using my PC.  My lighted keyboard and mouse suddenly go dark and quit responding.  I can be steaming video from my PC to my PS3 and that shuts down as well.  I can leave my PC idle and it'll work a few hours later, other times I go to grab a beer or something and when I come back the keyboard/mouse don't work.  I'm forced to do a hard boot because none of the peripherals work to shutdown properly.   It also happens while I'm typing or surfing the web.  It has to be a MB issue, but I don't see how this problem can suddenly appear after years of normal use.  I searched MSI's website for BIOS updates but they never work.  There is one available but I use their online BIOS flash utility and I get an error and have to restore a previous BIOS version.  I'm not even sure the updated BIOS is needed because it seems to be a simple upgrade for larger HDDs.  I'm stumped and I'm about ready to buy a new MB just to solve this issue.  I don't think it has anything to do with Windows.  I'm using XP and did a fresh install on a new HDD because my old drive was getting too old for comfort.  The problem still exists so I don't think it's some sort software conflict. 

[patio]

Control Panel/System/Device Manager/USB Hubs/Power Management...turn off Let Windows Turn This Off to Save Power...
Do this for all Hubs...
Stupidly enough this is the default Windows setting...

[ElementX]

I've done that in the past and the problem still exists.  I will double check to make sure I didn't miss any, though. 

*EDIT*
All of the hubs have that option turned off,  I appreciate the idea, though.  I've Googled a few times and can't find anything related to this problem.  Maybe my MB is bad and has to be replaced.

[Quantos]

Make sure that you aren't using any of the sleep or hibernate functions.  They can be very problematic on a desktop.

[ElementX]

I have all the standby/hibernate settings turned off, except for my monitor.