These are all hallmarks of spyware, malware, and/or trojans, not respected antivirus companies.
Or an error somewhere in the program.

I have win 7 64, and tested the method I posted before posting, and it was gone, so there may well be something wrong with the installation.

Also, I believe that the persistance of the gadget was an issue with a previous version - i.e. a bug, so what version of avast are you using?