unattended laptop enters random characters

[mike ma]

Every once in a while my computer enters strange things all by itself, following several examples:

7<31
pp723
<4
,<p,
78p8p

This can happen if I have a notepad open (Jarte), or a Word document (2003), or a browser (Firefox 35.0).

Sometimes I notice it after I wake it from having been in Sleep mode, but not necessarily always. It apparently can also happen when I just leave it on but without doing anything.

I have run the Sophos virus removal tool scan and it says the computer is clean.

Any ideas what this could be? Thanks.


Asus K95VB laptop, Intel Core i5 2.6 GHz

RAM 8GB
HD 7200rpm 1000GB
18.4" 1920 x 1080 display
WIN8 64-bit OS (with Start8 interface), language English, Keyboard Danish.

 

[C12Friedman]

I'm going to suggest malware as a possibility even though your AV program says no. Here's where it sort of falls apart, the first thing malware designers do is find a weakness in the AV program. Then, exploiting that weakness they disable the AV so it ignores their program (or maybe just quells all scans, meanwhile, appearing to scan).
Try this guide http/www.tomshardware.com/forum/8263-63-simple-free-guide-removing-malware see where you get