Did you check what kind of DVD+R's they are? Some info from
DigitalFAQ.com
1ST CLASS MEDIA
Almost flawless burns with 95-100% reliable results:
PVC = Pioneer = (-R)(-RW) ... media is no longer made
MXLRG01, MXLRG02 = Maxell = (-R)(-RW) ... be aware of fakes
TAIYOYUDEN, YUDEN, TYG01, TYG02 = Taiyo Yuden = (-R)(+R) ... be aware of fakes
MCC = Mitsubishi Chemicals = (-R)(-RW)(+R)(+RW)
TDKG02, TTG01 = TDK Corp = (-R)(-RW) ... be aware of fakes
2ND CLASS MEDIA
Decent discs, though not perfect, about 80-95% success rate:
PRODISC = Prodisc Media = (-R)(+R)
INFODISC = Infodisc Media = (+RW)
SONYD04 = Sony = (-R) ... be aware of fakes
RICOHJPN = Ritek or Ricoh = (+R)(+RW)
RITEK = Ritek = (+R)(-R)(-RW)(+RW)
OPTODISC = Optodisc = (-R)
FUJIFILM = Fuji = (-R)(+R)
3RD CLASS MEDIA
Quality can be very questionable, about 50-80% success rate:
LEADDATA, LD01, LD, LEDA = Lead Data = (-R)(-RW)
BEALL = Samsung BeAll = (-R)(+R)
MBI = Moser Beaur (India) = (-R)(+R)(+RW)
PRINCO, fake TDK = Princo = (-R)(-RW)
ONIDTECH = Unknown OEM = (-R)
MUST = Unknown OEM = (-R)
GSC001, GSC002 = Unknown OEM = (-R)(+R)
4TH CLASS MEDIA
Pathetic garbage media, landfill material, about 0-50% success rate:
RITEKG01, RITEKG02 = Ritek = (-R)
CMC, CMCMAG = CMC Magnetics = (+R)(-R)
PIODATA, PIO = LeadData, Ritek = (-R) ... once sold as "Pioneer" but that's false
Fake SONY, MXL = Fake Sony/Maxell from Hong Kong OEM (Infosmart?) = (-R)
OPTODISC = Optodisc = (+R)(+RW)
AN31, AN32, ANWELL, AN30 = Hong Kong OEM (Infosmart?) = (-R)
INFOSMART = Hong Kong OEM = (-R)(+R)
VANGUARD = Unknown OEM = (-R)
YIJHAN = Hong Kong OEM = (-R)
MATRIX = Hong Kong OEM = (-R)
VDSPMS = Unknown OEM = (-R)(+R)
LONGTEN = Hong Kong OEM = (-R)
ANYTHING ELSE = Unknown OEM or NEW
New medias to watch for: MXLRG03
Are there exceptions to this list? Sure, but not many. LD01 inkjet media and RITEKG04 inkjet media has proven to be almost flawless media for many users. But those are the only two we've seen as consistent exceptions. Use this list as a guide. This list is a "sure bets" kind of list, and is pretty reflective of the media market as a whole.
What do the % numbers mean? This list is constructed from many tests on many burners from a handful of experienced people that use a lot of media. These numbers reflect the number of discs in a spindle that will give good results. For example, out of a 100 spindle of media, 1st class discs may kick out a few bad discs (0% to 5% of the media may have playback imperfections or be outright bad burns). The 2nd class media may have a dozen or so bad discs. The 3rd class discs could give you a half-spindle of duds. And the 4th class stuff can be pure trash. These are mean averages too, simple statistics math, meaning best tests and worst tests are discarded, and the middle range of tests is the basis for these numbers. You may sometimes find the rare instance where a CMC spindle will be perfect and a Taiyo Yuden spindle will be completely flawed, but those times are the exception rather than the rule (and are not part of a mean average).
Testing procedures: Burns are subject to playability/reflectivity tests (usage tests), as well as software verification. Test equipment is under controlled hardware/software environments to eliminate user variables. Burns are at least 4GB or more to test the entire length of the media.