I set two recordings for the following times (my timezone is GMT/London):
05:55:00
09:45:00

and in the task scheduler set this program to run - "C:\Program Files\ProgDVB\ProgDvbNet.exe"

However, it only recorded the second one, the first program did not record at all.

I had it set to run with the built-in Vista administrator account.

I hibernated my PC, and let the task run, waking up the PC at the set times.

Anyone know why this has happened?

Thanks

I don't know if it is the same problem you are having but I set the scheduler to record three or four programs throughout the day on a daily repeat and most of the time they don't all record and you get a message at the side of the recording saying "failed" but it does not say way.

Do you have same problem without hibernated / sleep?

Yes

I get a similar problem too. I use the Hibernate setting (powercfg -h on) in order to stop physical switch-on/off of the machine when I need to.