>>>Hello,
>>>
>>>I was wondering how I could get a Uniqueness of Index Violation
>>>just by issuing a seek() command. I am new to FoxPro but I thought
>>>that the seek command just searched for a value rather than try to
>>>commit changes.
>>>The code is simple:
>>> select payment
>>> set order to pay_pk
>>> seek(x)
>>>When I pull up the debugger the line that causes the error is the
>>>seek() command.
>>>
>>>Any Ideas?

probably using buffering as ed said. try

use payment in 0 again alias lookup
select lookup
set order to pay_pk
seek...

when the record changes w/ pessimistic buffering, the information is saved.