Careful of the Saturday/Sunday thing - they screwed me with that- although it was still HP then. My last "working" day was a Friday, but the month ended on a Sunday. I was a salaried employee, so I never filled out a timesheet for Sat/Sun...in 20+ years I'd never logged a weekend as working time (although I'd worked a lot of them !!)
So three months or so later, I get a letter saying they'd overpaid me, as I had not worked the entire month (my timesheet did not show me working on the 30th or 31st). Even though I tried to explain that I was salaried, so didn't have to log those days... they maintained that as I had not worked the entire month, I had also not accrued the vacation time...so I owed them 2 days of pay, plus a months-worth of accrued vacation (another 2 days).
They then provided a calculation, taking my monthly pay, dividing by 10 working days in the pay period, instead of 31 days in the month (or the payperiod / 14 days) , and sent me a bill for a little over $2000...oh, and they reversed the annual 401k match because I was not an employee on the 31st...total hit, roughly $6000.
With the help of legal council and a LOT of written letters, we ended up settling for a lot less, but I still got screwed. I'm still waiting for updated tax forms - I still got taxed on the money they paid me...but then took back. I ended up having to file a statement with the IRS saying the company had refused to provide me accurate records...
I swear, if they spent more time making sure they did right by their clients and employees, rather than nickel & diming them at every opportunity, the company wouldn't be the swirling cesspit it has become.