First I'd get my antivirus program up to date, install MalwareBytes and get it up to date. Then boot to Safe Mode. From there I'd do a full system scan with the antivirus program. After that do a scan with MalwareBytes.
If that doesn't help, try Grif's suggestions here:
http://forums.cnet.com/7726-6122_102-5509131.html?tag=posts;msg5578829
Good luck.
After being on my computer for a while the drop down menus in dialogue boxes will drop down and then back up repeatedly in fractions of a second. I can often regain control by closing the box (like Windows Explorer) but the Start icon in the bottom left of the screen does not respond. Eventually all dialogue boxes do the same thing regardless of the program This problem gets worse and worse until I reboot.
Any idea where to start looking for the culprit?

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