It may sound stupid for me to suggest a thing like this to solve your persistent problem. However, I assume having done so much you can try this too!
I hope you have installed the driver provided by the manufacturer for your new DVD/RW . If not, please do it. Otherwise, to see whether the DVD is the culprit which makes the computer to hang, uninstall it first. You may do so by right clicking on My Computer , choosing Properties and then clicking on Device manager. Locate your DVD and right click. Do not forget to click on the + symbol first which will show your DVD/RW. Right click and from the menu choose uninstall. Ignore any stupid warning. Just click Yes. Now Reboot. If Windows autodetects your DVD and proposes to search for the drivers say NO for now. Work on your computer for some time and see if it freezes again. If so, then the problem lies somewhere else. However, if it doesn't then you can be sure that it was some faulty installation of DVD which may have caused the computer to freeze.
Now to install the DVD. Open the Control Panel and click on Add new hardware. A wizard will start and offer to install driver from your new DVD. If so, click 'No' and on the next screen instead choose to select the driver from the specified location. Now insert the driver CD you must have received with the DVD/RW and pop it in your CD Rom. Now pointing to the specified location install the driver.
Reboot once again.
Now see if all works fine