Hi Thirty and thanks for your post.
I'm not certain where you obtained information that violent crime was higher in Mountain View than the county average unless, of course, the average is higher due to the smaller population of Mountain View. Mountain View has only 72,000 residents (as of 2009), compared with 140,000 in Sunnyvale and more than 1 million in San Jose.
Also, everything truly depends on what you classify as "violent crimes"? According the Mountain View's site, there were slightly more than 2000 incidents of FBI Class 1 crimes in the city, but "zero" homicides in Mountain View. The bulk of the crimes were larceny--theft.
For more information about crime in Mountain View, check out their police site at http://www.ci.mtnview.ca.us/city_hall/police/crime_prevention/crime_statistics.asp
Remember that all cities will have crime. Because Mountain View is an affluent town with a median average income well above the norm in California and its located near the freeway, it may have a bit more larceny and theft than other more secluded towns like Los Altos, which does not have major roads into the town.
Good luck and check with the City's website for more information!
Grace Morioka, SRES
Area Pro Realty