Check IIS on your Task Server is configured correctly if it's IIS 7:
"Installing Task Server in IIS 7.0 or 7.5"
http://www.symantec.com/docs/HOWTO47804
And configure your sites to prevent too many clients connecting to the Task Server on the NS:
"Best Practice: Managing Task Server Communications in 7.0 and 7.1"
http://www.symantec.com/docs/HOWTO48411
The 5 invalid packages are from Deployment Solution, if you configure DS correctly they should populate, if you don't need DS it doesn't matter.
There are filters (Filters > Computer Filters > Task Service Filters) in the console that tell you how many Task Agents are connected to each Task Server, you can use the <NSName> one as a target for a Task to reset task agent and run that weekly.