When you visit iTunes' online store and search for music tracks, videos, apps, or games, the program automatically saves information about the pages that you visit in a temporary location called the Store cache. Problems may occur when the data stored in the cache becomes corrupt. You might notice that iTunes runs more slowly, and in some cases, it might even cause error messages to display. In these cases, it is strongly recommended that you reset the store cache.
This tutorial will walk you through the steps of the procedure.
Reset the iTunes Store Cache
Open iTunes, and click Edit > Preferences > Advanced.
Scroll to the Reset iTunes Store cache option, and then click Reset cache: