I tried to Burn a DVD with RecordNow software that comes with my HP
Media Center PC m7060n and I got an error. This happened for four
disks.

Now the DVD disks seem useless. How can I erase the DVD+RW disk and
use them again? Is there, software that I can use?

Hi, luciansurveyor.

Try this:
Insert the rewritable disc, double-click My Computer, right-click on
your DVD drive and select Format from the popup menu.

If that is not an option, check in RecordNow under the Tools section
for Format Disc.

If there's nothing there, either, you can use one of these programs:
http://www.dvd-makers.com/public/536.cfm

Please let me know if you need any additional clarification.

Thanks for choosing Google! Answers.

-bookface-ga

if your DVD rewriteable, you should be able to erase it using 
 nero burning rom version 6 or above...

here's one link for that program
http://www.download.com/Nero-7-Ultra-Edition/3000-2646_4-10474222.html?tag=lst-0-1

copy that link to your browser....
in that program... you'll see option to erase completely your DVD+RW

hope that would solve your prob