1. Most likely, i have deleted viruses form quarantine, then run a full scan and avg doesnt pick anything up.
2. Norton is rubbish, there are better free alternatives (AVG or avast), or if you want a paid AV NOD32 is a good one.
3. Temporary internet files are there so access to web pages is quicker as it already has an image of the page cached.
4. Who knows.
5. Older java patches are more prone to viruses. The lastest patch is Java 6 update 3.