More than two thousand University of Iowa students who work on campus got less money in their paychecks then expected this week. U-of-I payroll manager Joe Joynt says a computer programming error caused the students to be short-changed.Joynt says Social Security and Medicare taxes were mistakenly taken out of the checks that were issued to about 22-hundred students — making the payday smaller than usual. He says refund checks to make up for the error have already been issued. Joynt says students shouldn’t be greatly disadvantaged by the error. He says they may’ve gotten the refunds before they actually got their paychecks.Students who work on the Iowa City campus take on a variety of jobs, from re-stacking books in the library to slinging food in the cafeterias.