Data Validation & Time Format PROBLEM

[NoWhereMan2012]

I have a work timesheet which calcs hrs worked and adds travel time.

I had noticed that if I accidently enter travel time which is usually less than a hr with a decimal point rather than a colon I get the wrong time, I understand that but I thought I would set up data validation to prevent accidents that I could miss.

my cells are already formatted to "hh:mm"

with data validation, I set criteria to "time"
ignore blank=yes
data= between, 0:00 and 23:59

and I set an alert to stop with message.

I seem to be getting really eratic results

if I enter 1.15 I get the error message with choice to retry or cancel, the cell contents becomes selected ready to overwrite, if I click cancel it clears the cell or returns to previous correct state.
All Good, but if I enter 0.15 it accepts and converts to time giving a cell value of 3:36