RPR depends on your computer’s clock being accurate. If your date or time is more than 5 minutes off the current time, you will be unable to log in to RPR.
Why is this happening?
All modern computers have a Real Time Clock (RTC) unit installed. This unit has a small button-cell battery installed so your computer will keep the correct time even when it is turned off and unplugged. These batteries typically last a few years, then fail. You may notice your computer may start up with a date of 1/1/1900 and a time of 12:00 am.
Most modern operating systems connected to the Internet will also try to set the system clock by getting the correct time from a network time server. This typically happens within 30 seconds or so of your computer connecting to the Internet, so you may never even notice if your system clock is off each time you reboot. However, if you are not connected to the Internet or you have this “network time server” feature turned off, your computer will not update its time.