[dba-Tech] Excel Date/time problem

I am using Excel 2002 SP3 to list whats on my camcorder tapes-
I use one column to record the location on the tape (it is shown in hours, 
minutes, seconds, frames.
the hours are usually 0 sine that are 60 minutes tapes.
I have formatted the column as hh/mm/ss
something like 29 minutes, 3 seconds and 17 frames shows up as 29/03/17
this works just fine up to a certain line (31).
there it shows something like 05/03/17 and if I look at whats in there it 
shows 01.01.1900 05/03/17.

it doesnt help to mark the whole column and format it as hh/mm/ss.
but if I copy one cell with the correct format, then erase it and then type 
in the value I want, it works.

any idea, what to do to make it working from the beginning on?

thanks
Lembit