I had this problem and found that before I tried to burn the dvd, if I went to:
Start, run, type in Msconfig, and on the System Configuration Utility, change from Normal Startup to Diagnostic Startup. Then restart the computer.
This will then startup without the antivirus, firewall, etc. only the bare necessities, so DON’T go on the web until you do the same procedure, but restart in the Normal mode.
I found I could finally burn a DVD with this method.