Thanks! I downloaded identifier and had it check the disk I'd just burned and this is what I got:
Unique Disc Identifier : [DVD+R:MCC-003-000]
Disc & Book Type : [DVD+R] - [DVD-ROM]
Manufacturer Name : [Mitsubishi Chemical Corp.]
Manufacturer ID : [MCC]
Media Type ID : 
Product Revision : [Not Specified]
Blank Disc Capacity : [2,295,104 Sectors = 4,482.6MB = 4.38GB (4.70GB)]
Recording Speeds : [1x , 2.4x , 4x , 6x-8x]
See how it says 'book type' DVD-ROM? Does this mean that Decrypter did indeed burn the disk as DVD-ROM? If so, I guess my question is why the heck won't it play on my Sony DVP-CX870D: 300+1 DVD/CD??? Disks I burn will play everywhere else, but I thought that having the book type set to ROM would allow the Sony to read them as well.
As to my hardware set up, I have a Dell 2400 P4 2.66ghz, I have a 40gb HD, but I also have a 150 GB external HD that I've been saving the ISO too (then deleting).
My burner is the BenQ 1620 Pro, using Verbatin +R printable disks.
Since figuring out (via Fritzi's suggestion) to bypass Nero and use Decrypter to burn, I've had no problems whatsoever aside from the whole disks-won't-play-on-my-Sony DVP-CX870D: 300+1 DVD/CD-problem. Perhaps this is just too 'old' a drive to read disks, ROM or otherwise?
Thanks for the input!