First, ensure cell A1 is empty and goto Tools>Options and on the Calculation
tab check the Iteration checkbox to stop the Circular Reference message.
Next, type this formula into cell B1
=IF(($A$1="")+(AND(B2>0,COUNTIF($B$1:$B2,B2)=1)),B2,INT(RANDBETWEEN(101,110)))
it should show a 0.
Finally, put some value in A1, say an 'x', and all the random numbers will
be generated, and they won't change.
To force a re-calculation, clear cell A1, edit cell B2, don't change it,
just edit to reset to 0, and re-input A1.
--
HTH
Bob
(there's no email, no snail mail, but somewhere should be gmail in my addy)