USB Ports Not Working on MSI 875GTM, Can't Boot with PS/2 Keyboard

I have MSI 875 GTM-E45 motherboard in my computer. My computer is working absolutely fine from last six months. Since last week I am facing some issues in my computer. Suddenly USB ports in my computer stopped working and when I connect PS/2 Keyboard with my machine at that time my computer cannot boot and that is why I have to use USB keyboard in my computer. Main issue is my USB ports stopped working so I cannot use the USB keyboard also now please tell me what should I do to fix this problem.

I have gone through your problem I will suggest you to try one simple solution with your computer. You should try to solve this problem by uninstalling the USB drivers and installing it again in your computer and after that check whether your problem gets solved or not. if you still find the same problem then please provide me full specification of your computer which will help me to detect exact problem but first the given solution.

I am not able to reinstall the USB drivers because I am not able to use my mouse also. my computer specification is like I have MSI 875 GTM-E45 motherboard and AMD Phenom x3 8450 processor Western Digital Caviar 320GB hard disk and Corsair 2GB DDR2 RAM and i have SAPPHIRE 100254HDMI Radeon HD 4650 1GB graphic card and Antec Basiq 350W ATX12V v2.01 power supply unit. Now please tell me what should I do t fix this is. Is there anything wrong with my motherboard?

I have read your computer specification and after looking at your computer specification I would like to tell you that there might be issue with your power supply unit and I think it is not providing enough power to your system. You can fix this problem by changing your power supply unit. I hope this information is useful to you and you will be able to solve the problem as soon as possible. If you want any more information then let me know.

It sounds like there some problem with your CMOS battery and not with your power supply unit. I am telling you this because I had a same problem with my system and after that I have reset my CMOS battery and after doing that also I get the same problem and then I have replaced my CMOS battery and after that my computer is running absolutely fine and I mu not having any problem with my computer. I think you should also try this trick to fix your issue.

I have tried to solve the problem by resetting the CMOS battery and replacing it also but after doing that also I get the same problem with my computer. Now after doing that I have checked my computer by connecting different PSU and when I connect different PSU at that time my computer didn’t gave me any issue. Now I am looking for the PSU for my computer but I don’t know which one will work perfectly with my computer. Please suggest with which PSU I can go for.

As you have said in your post that you tried different PSU for your computer and after connecting that your computer worked fine and now you are looking for the good PSU for your computer then I have one suggestion for you. After analyzing your full system I think you can to buy Corsair VX450W PSU for your computer. It will provide enough power for your computer. I hope my suggestion will be helpful to you. If you want any more information then let me know.

I've the same problem with MSI 880GMS-E35. I restarted W8 and later al my usb port don't work. I've two OS (Ubuntu and W8) and my port worked ok so far yesterday.
I can use the PS2 port so I check the BIOS and the USB and the "USB Legancy" is enable. I connect an SONY USB media storage in Ubuntu and it works but in W8 doesn't work. Other devices don't work for example in W8 appears "Device can't mounted or something like that".
I don't have any idea of what it's the cause. I tried:
- Changing the power supply
- Changing the 3V battery
- Clear the CMOS memory

Please help me!!!!!