st: tabulate produces inconsistent output?

[Christian Raschke <crasch2@tigers.lsu.edu>]

Hello Stata-listers,

I am running into the following very odd problem: I have a factor 
variable that I would like to tabulate, but every time I use tab, I get 
different results. When running tab back to back on the same variable in 
the same data set I get entirely different results every time.
All the years that I have used Stata, I've never had anything like this 
happen, so I am totally stumped. There are only 2 variables in my data 
set: a variable "ID" that is storage type double and the variable 
"pldel" that is storage type byte.
Please see what I copied and pasted at the end of this email straight 
from my interactive session. The same oddity occurs if I use the .tab 
pldel, gen() syntax; in the same session I continue to get different 
results every time I run a simple tab, so the below are just two 
arbitrary examples.
If I open a new clean session of Stata, then tab works as expected. I 
did not define any user defined programs or do anything anything else of 
that nature in the broken session. The only commands in my Command 
History are various versions of <use>, <tab>, <count>, <describe>, and 
<browse>.
So, what might have happened to break a basic command like <tab>? I know 
that using a new session fixes the immediate problem at hand, but I want 
to ensure that something like this does not happen in any of my data 
analyses in the future!
If it matters, I'm running Stata 12.0 SE 64-bit on a Windows 7 machine.

I apologize if this has been discussed before, but a quick preliminary 
search turned up nothing. I would appreciate any help troubleshooting.

. tab pldel

   Place of |
   Delivery |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |    223,057       98.96       98.96
          2 |      2,191        0.97       99.93
          3 |        106        0.05       99.98
          9 |         46        0.02      100.00
------------+-----------------------------------
      Total |    225,400      100.00
r; t=0.08 13:15:07

. tab pldel

   Place of |
   Delivery |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |     62,726       99.41       99.41
          2 |        351        0.56       99.96
          9 |         23        0.04      100.00
------------+-----------------------------------
      Total |     63,100      100.00
r; t=0.08 13:15:11

. count
3765064
r; t=0.02 13:15:14


Best regards,

Christian Raschke
PhD Candidate, Department of Economics
Louisiana State University
crasch2@lsu.edu

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