Since you've already started using it to post I'm assuming you have corrected it for today. If you shut down and restarted now would it happen again or not till tomorrow?
A few things to try that may suggest the problems source (if someone doesn't come up with the answer, since I haven't encountered this since MSDOS days when ASCII had to be used for some things):
print out the chart and see if the letters are producing the numbers for their ASCII codes next time you start it.
when you boot take a look at your BIOS -the boot screen should tell you how by saying something about entering setup by pressing a key if you don't already know- settings and see if there is anything suggestive of a setting for this (DON'T change anything without knowing what will happen, but you can always go back to using the default settings if you do and mess something up. If yo do change anythng, make only one change at a time and see what effect it has so you don't have to wonder which change did what).
Try a different program when you first start to see if the numbers are in all of them or confined to just one.
BTW, what OS are you using and what are you doing to correct the number display when you first start getting them? How long has the problem persisted?
Leave the computer on overnight and see if the problem occurs anyway (meaning it is a scheduled task and not a startup one).
Further investigation of the OS, if that's a problem, and if you're using Windows would involve using MSCONFIG and doing a selective startup to see what service, feature, or initial program is causing the problem, like the BIOS, do not change anything till yo are certain and change one thing at a time. You could also try starting Windows -if that is your OS- in Safe mode (hit F11 before the windows screen appears while booting) to see if it is happening there as well. If it is not it is a driver or service being loaded at startup causing the problem.
(Hopefully, someone will actually know what is going on and have the solution at hand. Since it is easily corrected it is probably more of a nuisance than a real problem but still interesting to investigate. This is just how I would approach investigating the problem, it isn't necessarily the way it should be done.).
