My computer is a Lenovo ThinkPad L520, and is only a few months old. It runs Windows 7 SP 1. I don't know what made these problems occur, it just was there one day, and I can't link it to any new installations on my computer.
What happens is this: suddenly the computer starts deleting everything behind my cursor if it's in the middle of some text. If I click something on my desktop, it starts deleting everything behind the chosen icon. If I move the mouse over the messages I have in Hotmail (but without clicking anything), it tells me that I have to choose a message before deleting. This problem just occurs out of nothing. And there's nothing I can do to fix it. Then it suddenly stops again, without any reason. It seems to happen more and more often (I've only had the problem for half a week or so). If I choose something by clicking it, it tries to delete that and everything behind it. Luckily the computer give me a popup to ask if I want to delete, but then I'm stuck with continuous popups. This happens on the desktop, in task manager, in IE, well, in everything. Just writing this text has been difficult. I have also experienced a few times that the computer just thinks I am pressing Tab (or at least I think it's that). There's no key stuck, as it all is nice and smoothe, because the computer still is new. I have NOT spilled Coke in the keyboard, as I normally do with my computers. ;-) How many times I've tried to reboot, I have no count on, but it doesn't help.
I have searched through the computer for viruses several times (using Avast - up to date on virus definitions). I've searched for malware and spyware (using Spybot and SuperAntiSpyware). They haven't found anything nasty, and it has not helped at all. I've checked event viewer, without finding anything I can link to the problem. There is not a single warning or error in the system log, and a few errors in the program log, but I can't seem to link them to the problem.
I am now at my wit's end, as it really prevents me from using my computer when it acts like this. Even taking a backup is pretty difficult, as it can only be done in the periods where the computer is acting like normal again.
I have NOT tried to reinstall Windows, as I am hoping I won't have to. I am new to Windows 7, so I am not used to coping with problems in this OS. I am used to working with Windows XP and older versions.
And now, suddenly it works smoothely again. I have no idea why. But I struggeled with the problem for 1/2-1 hour before it cleared up again.