...from: http://www.macworld.com/article/142752/2009/09/itunes9_safari.html
Bugs & Fixes: iTunes 9 and Safari mix it up by Ted Landau, Macworld.com
After installing iTunes 9, you may find that the updated version refuses to connect to the iTunes Store.
However, at least based on my testing, you don’t need the actual Safari application for iTunes Store access. For example, I deleted the application from my drive and the iTunes Store worked just fine. My guess is that there is some installed component of Safari, located in a Library folder (WebKit framework?), that is the true requirement. It is this that needs to be the proper version. Unfortunately, I have not yet determined anything more specific.The cause turns out to be a direct link between the iTunes Store and Safari. Specifically, you need to be running Safari 4.0.3 or later to access the Store within iTunes 9. If not, you’ll be greeted with a message informing you that you cannot “use the iTunes Store within iTunes.” You heard correctly: you may need Safari installed on your Mac, in order to use the iTunes Store, even if you otherwise never use Safari.
Reinstall Snow Leopard? For some users, the news was even worse. They were getting the Safari warning message even though they had Safari 4.0.3 already installed. Based on threads posted in Apple Discussions, most of these users appear to have been running pre-release versions of Snow Leopard (Mac OS X 10.6).
The solution turns out to be to install the release (golden master) version of 10.6. Even those that claimed they had previously installed the golden master version generally found that re-installing the OS from a release version DVD eliminated the error. If, despite following all of this advice, you still have this symptom, I have no solution to offer at this time.
No Genius Mixes? Although more subtle, a second iTunes Store problem also turns out to have Safari files as its root cause. The specific symptom is an inability to get the new Genius Mixes feature to appear in iTunes listings.
The first potential fix for this omission is to go to iTunes’ Store menu and select Update Genius. If that does not work, return to the same menu and select Turn Off Genius followed by Turn On Genius.
If things go well, your work is done. However, in some cases (including my own), things may not go so well. Turning on Genius may get bogged down in Step 2: Sending this information to Apple. If so, a message politely informs you that “This seems to be taking longer than usual…” In fact, left alone, it will likely never complete.
The solution here is to delete the relevant Apple cookies from Safari. To do so, quit iTunes, go to Safari and select Preferences -> Security -> Show Cookies. In the search text box enterapple.com. To be extra sure of getting the job done, you can select all of these files and click to Remove. Otherwise, you can start by removing only the .phobos.apple.com items(s), as well as any other items that contain the word “itunes,” and hope that is sufficient.
After doing so, return to iTunes and once again select to Update Genius. With just a bit of luck, all should now proceed smoothly and Genius Mixes will appear within a minute or two.
Updated at 9:16 a.m. to clarify a potential fix for the Genius Mixes bug.