iTunes is 'not responding' on startup

Running windows vista , just downloaded and installed iTunes a couple hours ago , while i was sorting my music there was a pop up about lack of memory or something , then it got really laggy so i closed it . And now when i try to open it it opens fine but just sits there and is 'not responding' according to task manager .

If someone can help me beat this piece of s#*% program back into shape i'd greatly appreciate it .