I use a Compaq C300 Laptop from pre-Hp & Compaq Merger days. And it worked fine all through except for 2012 onwards when I first encountered This Problem I'm about to Mention. Prompts started showing up about turning Sticky Keys on or off since I pressed "SHIFT" key Five Consecutive Times at Starting my laptop When I hadn't touched those buttons at all!Continuing further, typing anything became almost an annoyance because apparently Shift Keys were still pressed & words appeared in caps & anything I clicked with mouse was selected with everything up to that Icon & every one of those Softwares opened a Prompt box!Most Shortcut keys work with Shift, CTRL & Function Button too!At the time,I used an External Keyboard via USB which seemed to function well for first couple of Restarts,accessed Safe mode with a LOT of difficulty&restarts &ran antivirus since I suspected I was a Victim of a Viral Program or Worm Attack!I found nothing major wrong after lot of different Antivirus scans!In the end I used "Last Known Good Configurations" options & it went back to working normally!I eventually changed from Win-XP (2007 ver) to Windows-10 in 2017 & My laptop has been Reformat once since too by Repairmen! However,in 2018, My sticky Keys errors have returned & I write this Question on Forum using Safe Mode Browser too,where all executable programs are disabled!How do I solve this Problem? Keys are already set at default & this time, I don't have an external keyboard for my laptop. A "keyboard Test" software helped me identify it's my Left shift Key being constantly pressed while I'm not even sure its stuck or pressed that hard! (I clean the Keyboard using Spirit sprays too). I took a Screenshot of the Test but see no way of attaching it here. However,It seems to be a regular problem judging by Forums, How do I solve it, esp using BIOS options?