Another rather technical entry, but as I ran into some trouble and had a very hard time getting it fixed, I can only assume others may run into the same, hence more information is better.
I run Ubuntu on my laptop and had the superb idea to install the AVG free antivirus program, which totally failed. After downloading the package, I ran into an error that told me the file could not be opened. When I launched the package-manager again, it complained that the package avg75fld was broken and couldn't be found. Running sudo apt-get clean from a terminal window didn't fix a thing and my package manager remained as broken as it could be.
After searching the ubuntu forums, I was finally able to get rid of the error and the broken package by running sudo dpkg -P --force-all avg75fld from a terminal window.
Note : according to the thread in the forums, one should not use this option lightly as forcing a remove could lead to all kinds of problems, so it is clearly a case of user beware!
Anyway I took the plunge and got rid of the avg package. While the scanner performs well on most windows systems, I'd suggest steering clear of it on linux!