Windows 7 write speed too fast or too slow

This is my first post. Thank you in advance for your help.
I'm an xp vet and want to be a win 7 expert.

Using:
windows 7 evaluation copy build 7100
Amd athlon 64 x2 dual core 5000+ 2.61 ghz
2 gb ram
lite-on DVD writer
Memorex dvd+r

I had no problems using this combo with xp, but I've only been able to burn one dvd succesfully using 7.
My success came from Windows DVD Maker
I'm now trying to burn an .iso using built in software.
I am also a huge fan of ConvertXtoDVD but have not been able to burn so far.

The Error I currently have with the ISO says "The write speed for the recordable disc is either too fast or too slow for your DVD burner. Insert a recordable disc that has a different write speed, then try again."

I repeat I had NO PROBLEMS WITH XP using identical setup.

Any advice would be greatly appreciated.