When I burn DVDs using DVD-R's, the discs mess up. But with DVD+RW, it works perfectly. What gives?

What is the brand/model of your drive? Are you using the same brand/series of blanks for both -R and +R? It seems unintuitive as generally -R should be more easily handled. When is the last time you updated the firmware of your burner? The drive's firmware has the burn protocol optimizations for the different brands and series chemistries and when an update is available, a lot of the code is for burn optimization. I'd say that if a firmware update doesn't fix the problem, then look into a new drive. Luckily they don't cost much any more.

.bh.

It depends on what your DVD burner supports. Just go with whatever your burner supports and upgrade to the newest firmware/driver for your burner. DVD-Rs and DVD+RWs are different in a way, and not all DVD burners supports both types. Worse case, get a new DVD burner.