Another computer question?

Yes, another question from someone who can’t function without them but does not really understand them.
My work computer has developed a nasty habit. As I type, the words may, or may not, appear on the screen. Sometimes nothing will be there and several seconds later what I typed will show, other times it seems to skip over several letters and then there are the times when nothing shows, ever.
It does this offline, using mostly Excel or Word, and when I am online. Online it is most aggravating trying to enter passwords and if I jump from one page to another it is like the computer is trying to catch up but not there yet.
I have not added nor deleted any programs, probably within the past two years,
It is a Dell and uses Windows 7. Now, I do have a virtual machine within that runs the old Windows XP that rarely gets used but was added to access an older program will still refer back to from time to time.
I have scanned it using Malware Bytes, AVI and MS Security Essentials and have come up with nothing.
I am beginning to think it is a hardware problem with the keyboard. I use a wireless keyboard and mouse, have checked out all the connections, made sure they are all tight and even put fresh batteries in to no avail. I do not have a problem with the mouse,