ASUS Laptop P key generates an asterisk

This is a hardware problem in the scan lines for the keyboard.  Either the keyboard (very likely) or the keyboard controller (not very likely) is defective.  To troubleshoot, swap the keyboard with a known good one and see if the problem goes away.

If the system is under warranty, this would be a covered defect.

Thanks. What's the quickest way of swapping my laptop's keyboard? Is there a spare one hidden somewhere?

What version of laptop?
You just turned on Num Lock, and your laptop don't have numeric keypad.
Turn off Num Lock should solve your problem.
:)

Your keyboard is probably not defective. Likely, it's in NumLock mode. Many laptops do this. It allows you to have a numeric keypad. Look for a NumLock key and tap it to turn off NumLock mode (it's a toggle — one tap turns it on, the next tap turns it off). Regards, Joe

Good catch.  I never use NumLock on a laptop.

you can test in several ways :
-test with an  external keyboard will show if the problem happens too; if yes, it is a software problem
-test the keyboard when booted from a live cd , like knoppix : http://distrowatch.com/table.php?distribution=knoppix

Depending on Asus model
Press Fn or Shift + NumLock to toggle the key assignment.

Thanks guys.  I have an ASUS Q301L (read from label on the back). I bought it 14 months ago at a Best Buy. It does not appear to have a numlock key.

I have attached a photo of the keyboard.

I must have hit browse to locate the image but neglected to click on the Upload button. Sorry about that.

Your explanation sounds quite feasible since when at home, we use a Targus USB 3 dock connected to a full size MS sculpt comfort keyboard and mouse.

I will try and find a keyboard to toggle the numlock key. We discovered that you can enter a P by holding down the FN key and pressing P. In fact, if you hold down the FN key on the other problematic keys, you get the correct result. We can live with this until we get home.

Will report back when I get the chance.

Many thanks for your helpful comments.

Just run script and you don't have to wait to come home.
:P

Another approach is to run this VBScript:

set WshShell = CreateObject("wScript.Shell")
WshShell.SendKeys "{NUMLOCK}"

To give credit where credit is due, that code is from here:
http://www.tomshardware.com/answers/id-2115797/asus-vivo-keyboard-displaying-incorrect-characters.html#14271972

Regards, Joe

Code is not from there. :)
It is easy to paste code in search engine - it will find some match.
Actually it is from here to give credit where it due.
But you can find it on many locations when you paste code into search engine.
It is some time in my bookmarks in the case I need it, along with this one for other keys.
:)

To be clear, I didn't paste that code into a search engine. I hadn't even looked at your attached file until now. I found that code when I was searching for a picture of the keyboard. In terms of sending keys more generally, I use the excellent (and free!) AutoHotkey. Its list of Keys, Mouse Buttons, and Joystick Controls is here:
http://ahkscript.org/docs/KeyList.htm

Regards, Joe

Back home now. Connected the laptop to the dock and toggled the external MS Sculpt keyboard's NumLock and presto! Problem solved.

That's great news! Always nice when it's a simple fix. :)

Yeah Joe Winograd's solution and explanation works.  I have Asus Zenbook on Windows 10 July 23, 2016.  I had exactly the same key morphs as the original question - p becomes asterisk; zero becomes slash; slash becomes plus.  I found the on-screen keyboard and sure enough it showed NumLock as on.  Turning it off fixed the problem.  Saved me from switching out keyboard, searching for malware, etc. etc.

Glad to hear that, Member_2_7969006 — thanks for the post! Regards, Joe