There are a couple of things to check:
1.) latest firmware for your burner.
2.) other programs, like Nero, or Roxio, that can get in the way of the burning process
3.) the brand of blank media can make a lot of difference. I recommend Verbatim, or Taiyo Yuden, and recommend against Memorex, TDK, or any store brand.
4.) can you Burn to Folder?
5.) is any part of your Project on a USB external, or on a networked drive?
Just some thoughts, and good luck,
That you are getting the error when writing a folder means it is unlikely to be the hardware. Because it used to work I suggest for a first step you uninstall and then reinstall PRE8.
If that doesn't fix it post back here with more information about your PC, the source of your video clips and how you got them onto your PC.
Insanity is hereditary, you get it from your children
Also note that most MP4s -- such as those from Flip and pocket camcorders -- will not work in Premiere Elements.