skeetskeet, if you wrap your posted PHP code in [ PHP ] [ /PHP ] tags it will make it much easier for the rest of us to read and be able to help you.
The code itself looks fine, although it does seem to me to be a little strange to have a timestamp for when the form is requested rather than when the form is posted. But syntactically it's correct. I think it must be a database issue. I'm guessing your 'timestamp' field must not be INT, or at least not an INT field large enough to handle integers like 1121920018, for example. That's a UNIX timestamp of approximately right now.
This
echo date("l F d Y", 1121920018);
will result in
Thursday July 21 2005
(and do you see the difference in [ PHP ] vs [ CODE ] tags?)
Can you tell us what the datatype is for your 'timestamp' field, and give us some examples of the values in a few rows?
EDIT: BTW this
echo date("l F d Y", "crap");
results in
Wednesday December 31 1969