@ Jebb S. Talle
If the reboot didn't resolve it - Try a repair of avast:
Vista, win7 - Control Panel, Programs & Features, uninstall a program, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow.
You may need to reboot after the repair.
However, if avast is showing as running in the Task Manager and in the avastUI, e.g. all elements are running ?
Then the problem is with the Windows Action Center and that is not unusual.
What firewall were you using before you installed Avast Internet Security (AIS) and how did you remove it ?