The process cannot access the file

Hi to all, I have created one zip file programatically, after some time i check whether the files exist then delete it and create a new file, here while deleting the file it raise an error as below

Exception:

{"The process cannot access the file \"MySharedFilePath\09.zip" because it is being used by another process." } System.Exception

StackTrace:

StackTrace "   at System.IO.__Error.WinIOError(Int32 errorCode, String str)\r\n   at System.IO.File.Delete(String path)\r\n   at MyMethodname string

I came to know this is due to if the Filestream is not properly closed but in my case i have closed everything perfectly, i'm using Windows XP,.

Experts please tell me, what is this problem and how to solve the problem, last 4 days i was trying but no luck, so please help me.
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