I'm using a couple of laptops - one is nearly three years old and for some bizarre reason only the "M" and "N" keys are loosing the symbols printed on the key. I could understand if the vowels were wearing out.
Someone helpfully suggested that I probably type "M" for "Microsoft" pretty frequently but in that case surely "O" would be even worse.
I've heard of more and more people who are finding that they're wearing out laptop keyboards and power supplies as often they're powerful enough even though they're several years old.
Of course the increased use of virtual machines for testing purposes on laptops does tend to demand additional power but for general purpose use it seems that rarely is the latest and greatest hardware required.
You're lucky! I've almost got no E, only half an A and the S is fast disappearing. Only a very small corner of the N key is missing and the microscopic part of the M is worn away.
Are the m and n keys being rubbed by your right hand thumb while typing away on keys further up the keyboard?
I'm tempted to say it's from answering "Do you want to install this package on your computer? (Y/N)", but more prosaically, it might be "Next" that's making your N key wear out.
Admit it, you've got some dodgy port of Daley Thompson's Decathalon game and you're trying to beat the record :-)
Nik> Ah I remember that - a blast from the past.