Why isnt my girlfriend talking to me much anymore?

We have been dating for 5 months a 13 days... And now, I dont have a single clue why but she has just been very stale towards me... I rang her abour 10 mins ago and she said it was nothing. I love her so much. Honestly. I just want to know why she isnt talking pretty much at all anymore. For example. The other day when i was talking to her on MSN I said I got 3 new cannibal corpse albums and she just said "ok". I mean, if she wasnt interested in me anymore the least she could do is tell me so I could gouge out my eyes faster but she is still interested in me. Oh and there is nothing going on with her family and friends and stuff cause she would have told me. There would be no stress from school because we have a 3 week holiday. I dont know what it is. We used to talk on the phone for hours literally and the max ive managed to get now is 4.30 seconds. This is seriously depressing. I dont want to break up with her, but if I keep being unnoticed by her, I think I might have too. Thanks.