I have had this, too. I agree with bird dancer that it can change with time. Moods, meds, hormones, and whatever this autoimmune type thing I have is all contribute to my changes in cognitive functioning. After what my doctor said was a mixed episode plus a med reaction there was a week or so I could not do basic tasks like download a file from my computer. Seriously, I lost some of my school work when they cleared the drives because I could not execute a basic thing like that. Today is a good day for me and I can focus clearly, feels great. This is just my experience of course. I am sorry you are dealing with this. Definitely something to ask your doctor about as I am sure you know. There are many possible causes.