Thanks for the reply mciachel!
Yeah I know that laptop drives are generally crap, but I just wanted to
use up all my options before resorting to an external drive. ( The irony is that with all the money I spent on DVD+R DL so far, I could have bought an external drive!:/)
About the speeds: By using MSCE I found out that the dell and toshiba firmwares have burning strategies for MKM 003 discs at x2.4 and x4. The samsung firmware also included x6. However with whatever burning software I use the available speeds are only x3 and x4. I tried burning @x3 with no luck.
Another thing that might be worth mentioning is that I burned a couple MKM 003's in Ubuntu 8.04 with the same results (coasters). So I guess its not a software or firmware problem.
I also noticed a thin 'ring' on every coaster towards the outer side of the disk.
The bottomline is probably that the drive is of very poor quality?
PS: Thanks for the guides btw