Hi, Just want to know something as you named the post 'device manager prefect but windows 7 says no dvd' Do you have any problem with the DVD drive?
In your last post you said 'the device alarm which is the sound i hear and causes the freeze happened every few minutes freezing the system in whatever task i as doing. ' Is your computer beeping? If it is beeping then there is a hardware failure.
You can go to the 'Event Viewer' to check for any information of errors. Go to start menu, then type in Event viewer.It will come up.
Have a look on the left hand side panel, find Windows Logs, double click on it.
Select Application and check on the right panel for any errors, exclamation marks.
You can also select the System and Setup, check for any critical errors and the information.
If you want to make a screenshot of the errors you have then press the PrtScrn key and then paste it in Paint save it and post it here.
If you cannot find any errors on the logs and the computer is not producing any beeps do the following: Unplug all the usb devices (printers, scanners, everything) except from the keyboard and mouse. Do not leave any other usb plugged in.
Now follow this steps:
Install Windows
Download and install SP1, reboot.
Check how it works.
Before installing anything else check how the computer works for a while and check your device manager that it doesnt show any exclamation marks or red signs.
If it works ok then download the drivers for your USB things from the manufacturer website, make sure you download the win7 version.
I hope it helps as it is a weird issue.