sorry i didn't get back to you sooner, iv done some research and it could be one of 3 things
1: your burning software is incompatible with Windows 7
2: You are missing a vital
driver
3: The burning laser of the drive has failed (though i hope its is not the case)
I would be tempted to check Device manager to see if any
drivers need installing, the will generally show with a yellow "!" where the device need attention
In filing that there is no issues you may need to look for another Burning software program (Nero trial will be ample for testing)
If all 1 & 2 above fail, it may well pay to try another drive, if you can not get another drive for testing an new one should cost around £30 top line