Sorry for my English.
I have dell optiplex 390 computer. I used it for 6 month without having problem. But now i have problem on keyboard and mouse. Every time turn on the computer it work correctly for 2 or 3 minutes. After that it stop responding. First I thought it have problem with OS. Then I installed windows. But now also it happen as before. When it happen I change the port that mouse and keyboard are connected. Then it again work for 2 or 3 minutes and stop working. I check whether the port I used before can used for other devices so I insert USB flash drive. It detected. So I am confuse what the real problem is. I hope will get your help soon.