big sorting issue

I hope someone can help me this problem has been plauging me for weeks now. . . i only have four columns total and i select the entire sheet, sort data by column A (the other columns don't really matter) and i get MOST items sorting properly. . .then i get this


45401800 /MKT "Cheri" /Feb-97 /19
77661421 /BNSF /May-00 /19
77670513 /Union Pacific /May-00 /19
0020 /Reading /Jan-97 /19
0105X /Lamppost /May-99 /19
0132X /Revolving /Apr-00 /19
100 /"Continental" /Feb-97 /19

and that happened around cell 1928. everything else is in the right order but that. If i cut the data out, paste into notepad, resort, then repaste all the info in and sort it again, it usually fixes the problem, but not always. anyone have input on how to resolve this?? i tried formatting so it is all text, all numbers, checked for spaces etc and am totally frustrated now.

(some of the data is from excel 97 (?) and the rest is from 2000. i'm using 2000 currently)

(just wanted to bump this up incase no one saw it, i've now tried various websites and books and still have no answers)