SEP (build 4126) won't install

The standalone install goes most of the way through; then hits a certain point and rolls it all back.

I can't get the SEP_INST.log file here yet; the machine doesn't have CD/DVD burning enabled yet (driver missing) and I can't use an external device to pull it off (also driver missing).

In the interim, while I track down the drivers, it's failing on the following section:

\scripts\startup.sis

And then goes straight into failure and rollback.

I'm ~very~ willing to take "well, it might be this" type suggestions while I get the log file over here.

Thanks!