http://www.javacoolsoftware.com/spywareblaster.htmlThis is a prevention tool. Also, with Spybot Search & Destroy, have you run an immunization recently? This stops a number of things.
Some random advice ...
One among many problems with spyware and adware prevention is that what constitutes these things can come in many forms. Cookies, for instance, often show up as data miners or the like and will cause a hit on a spyware scan. You get cookies from websites typically, so given the frequency of your problem I suspect you are visiting a website daily that sets one of these cookies that shows up as spyware. You either didn't say this, or I did not read carefully enough. Are the repeat instances of spyware always or usually the same thing, or are they different? If they are the same or at least similar, I suspect very strongly this is the problem. The default home page for IE, for example, sets a cookie that detects as spyware. Many major news organizations have the same issue with their websites; they generate revenue this way.
If this is the issue, the most solid solution is not the easiest. You need to determine which website(s) you visit are setting these cookies. Then you need to use a browser or firewall that lets you block cookies selectively. A more drastic solution would be to disable cookies entirely, but this can cause problems with a number of websites that rely on them for full functionality. I can't do online banking, for instance, without a cookie being set.
Now, if the spyware is coming in the form of executables (programs) stored on your computer somewhere, and if this is happening every day, you have a far more serious issue. If you're not getting this from installing "free" programs, utilities, screensavers, etc. that come bundled with spyware or adware, it's getting on your system in a way that could suggest you've got a hacker/trojan/virus problem. If Norton is your only virus scanning tool, do not rely on it to have caught it all. As mentioned elsewhere, I cleaned a system that had Norton installed that had 11 distinct viruses/trojans and hundreds of individual instances of spyware.
All that said, even with the best methods available, you're not going to stop all forms of spyware and adware unless you basically go into ultra-secure mode and manually inspect every single bit of traffic that comes across your internet connection. A lot of it isn't malicious; it's simply intrusive and provides a potential security risk if your system becomes infected with something else. Until websites figure out another way to generate income, it will be with us.