How much free, defragmented space is on your hard drive?
Programs like DVD Architect often need a lot of scratch disc space to open and operate. 20-30 gigabytes should be the minimal you keep free on your C drive. And it should be contiguous free space -- which means you need to ensure it is defragmented. Fragments can break even 30 gigs of free space into tiny, unusable chunks.
And if that doesn't work, I'd call Sony. Something is apparently not triggering here.
BTW, you aren't using an operating system like Windows 7 64-bit, are you? The drivers for that operating system is still evolving and may not work perfectly with DVD Architect Studio -- although this would be the first I've heard of it with this particular program.