Java Programming

I have a strange problem. I deal with different files of different formats including, jpg, bmp, png, zip etc. I am able to successfully create it and do the necessary processing of those files.

But, when i try to delete the files, am not able to delete specifically gif files, while i am able to successfully delete other files. I don't have any security manager, and no security exception is raised. Yet file.delete() returns me false [I use Java 6 for your info]. i have this problem only with gif files. Any ideas?

Sreram