Nero takes time sometimes, if the file isn't exactly a PAL or NTSC vcd.
I suggest u use NeroVision Express for it. Atleast it shows what is goin on.
Also to convert files, or change resolution, improve video, use
TMPGEnc. Then use Nero for burning.
Ulead also is a great help. Also VCD Gear. The former can burn the disc 2 & the latter can make the iso file for buring on any burnin sw.