So I've got Win XP, after startup I'm unable to run many applications (like Google Chrome, Opera, Lightroom) while some (Word for example) are running OK. If I make a scandisk (during bootup) the things get fixed, but only till the next reboot, when everithing's the same again. Any idea? How can I diagnose the problem?
As a precaution, Back up your data and prepare to have hard d rive failure. Install Speedfan and see if there are any SMART errors.
You can also download and run your hard drive manufacturers diagnostic tool to test the hard drive, back up your data before doing anything else.
If the hard drive checks out OK, I suspect Malware, see my post here