Why not add this to your original post for this issue? http://forums.cnet.com/7723-6122_102-616997.html
Also, a few more details about what exactly is going on. Give a sample scenario starting from your computer in the off position and you pressing the power button. Work your way from there to what issue you are describing, because it seems like you could be talking about at least two different possible scenarios and to be of any help to you at all, we'd need to be sure which one it is, or even if it's a third option.
Add all of this to your original post rather than creating a third.
After using pc more than 5 minutes. If I restart it, then it doesnt boot up, nothing shows on monitor, but cpu fan is on, And i think other things are also on. After taking some time (depends on using pc, before giving restart command) it starts
G41 combo (gigabyte)
Dual core 2.7GHz
350W power supply