My Iphone4 recently has a very abnormal problem which I have never heard of. The Iphone screen goes blank. I try to reset it many times and it does get reset but same thing happens again. Infact If I keep it idle then it works but again same thing happens

Yesterday Suddenly my Iphone4 screen went blank. It had happened a few times earlier but I reset the Phone and it worked fine thereafter. But from yesterday a typical behaviour of Iphone is seen. The screen goes blank and even on reset the screen does not return. Infact if the phone is left idle for sometime and then if Home buttong or sleep/wake button is pressed then the screen appears again. But it stays for a short time, maybe for 5-10 seconds only and within this short time I can do whatever I want to on the phone. Thereafter the screen goes black again. Hence same process needs to be repeated.

Please suggest the possible causes for such malfunction. FYI the Iphone was working normally till this time and no new applications were installed in it from the past 1 month almost. The regular updating was done and the software is most up to date. The Iphone is shown when connected to Computer on Itunes. No major change in environment was made and no dropping or any unusual thing happened to this Phone prior to the occuring of this problem.