My Asus and Acer netbooks would occasionally do this under open office, and I assumed it was an open office issue. When I moved to win8Dev on both of them the problem went away, so I am not sure how to fix it; but I never noticed it outside of open office.
Thanks caedenv for response. Have moved the PC to another location and thus wireless network and still having the same problems. The problem occurs when browsing the internet and typing anything into the fields on web sites, not unlike this one.