I know there's a firmware update, but reading the changelog ("Improve Writing Strategy for new 20X media") it doesn't seem like it's gonna fix this problem and I don't want to take the risk. It used to work ok.
Media is not very high quality, but a friend of mine is using the same discs with two drives (one is a SATA LG drive, can't remember if it's the same model) and he never had any problems.
BTW, it's a SATA drive working in AHCI mode.
I canceled the operation and after almost an hour, it finally stopped (the drive's light was still blinking):
I 16:43:33 Abort Request Acknowledged
I 17:41:02 Synchronising Cache...
W 17:41:05 User opted to skip the 'Close Track/Session/Disc' functions.
E 17:41:05 Failed to Write Image!
I 17:41:05 Exporting Graph Data...
I 17:41:05 Graph Data File: C:\Users\User\AppData\Roaming\ImgBurn\Graph Data Files\HL-DT-ST_DVDRAM_GH20NS10_EL00_JUEVES-30-DE-OCTUBRE-DE-2008_04-12_p.m._MBI_03RG40_8x.ibg
I 17:41:05 Export Successfully Completed!
E 17:41:05 Operation Aborted! - Duration: 01:28:48
I 17:41:05 Average Write Rate: 604 KB/s (0.4x) - Maximum Write Rate: 11.141 KB/s (8.0x)