Trying to enter Duration time in Stretch and Pitch - no good

I've been trying to manually enter a Duration time in the Stretch and Pitch window, and it's not working.  For example, I want to enter a time of 19 minutes and 15 seconds.  I enter 19, then a colon, and I start to enter 15, but as soon as I press the number 1 key, the total duration fills out at 19 minutes, 00.999 seconds and the cursor jumps back to the left end of the number.  I put the cursor on the first zero and hit the delete key, nothing gets deleted and the cursor jumps to the left end of the number.  But what's weird is that the duration changes from 19:00.999 to 19:00.998.  Every time I go back to the first zero and hit the delete key, the fraction goes down by 1.  If I put the cursor between the two zeros and hit the delete key, same thing, cursor moves to the beginning of the number and the fraction goes down by 1.  I try to put the cursor on the first zero and type a '1' without hitting the delete and the duration changes to 20:40.998!  If I try to enter '1915', the field will fill and the number inside is 31:55.000!  This is driving me nuts!  What kind of gremlins are in this field!  How do I get this duration to the numbers I want, namely 19:55.000!  Does anyone know what may be wrong here?