Having trouble to write 2 alike letters and to delete what i right

I'll agree it sounds like your system is being bogged down by malicious software i reccomend downloading and installing a free anti-virus software. Once you have an anti-virus software installed you want to update to the newest virus definitions just so you can get all of those pesky little things out of your system all at once.I've heard AVG works well and if free personally i like norton but it's costly. If your problem still continues pick up a can of compressed air and clean your keyboard but it sounds like a software problem not a hardware problem.