The process cannot access the file because it is being used by another process.
The error happened because when you try to access an object of image or Font just immediately after you use it. Because the dot net framework does not destroy the resource before you calling. To resolve this problem you have to release the resource first & then you can use it again. To ensure freeing the unmanaged resource is a tough job but doable.
So it would be better to practice always wrap up your relevant code within "Using" statement.