Avast Internet Security blocking internet access

Hello, I have recently updated my Avast Internet Security copy on one of my two laptops, a Lenovo Thinkpad with Windows 7. Now I find that, while the wireless icon confirms that I am connected to my network, there is the yellow circle indicating no connectivity. The other laptop has no issue. I tried ipcongif to no avail. I tried uninstalling Avast. I looked for possible programs that could be causing this. No solution in sight. What could be wrong? What should I try next?
