Can I interrupt an rdiff-backup backup?

Hi

I've just started using rdiff-backup (rd-b), which I think is a great 
program.  I started an initial backup that I expected to take about 3 
days, but during the night my computer decided to reboot or at least 
close down the window running rd-b (amongst others).

I have re-started rd-b but as far as I can see there is no disk activity 
at all on the local disk. There does appear to be some activity on the 
Server (remote disk) which makes me think that rd-b is caught in an 
infinite loop of some sort.

I do have a log file logging activity that is in a directory that is 
being backed up.  I mention this in case this could be a cause of problems.

I am unsure what to do next.  Is it ok to crash out of the program?  If 
I just restart rdb, will it automatically correct the problems?

Your advice would be much appreciated.

Regards
Mike Hart