Delete Temporary Files Using Asp.net?

In my application,I have some reports which needs to be viewed frequently.After viewing the reports many times by different users, it shows load error.For different systems, many temporary files are created.i need to delete those files in my single system.now i manually deleting all the temporary files in the temp directory and configure the IIS again.then the report loads properly.But we need to delete these temporary files frequently which makes our life dreadful.Only the report files needs to be deleted.How can i delete these temporary files automatically using code? I have used the following code for this.but some files cant be deleted as those files are in use.Do those temporary files in other system can cause load error in our system?

dim temp as string=Environment.GetEnvironmentVariable("TEMP")
dim k as sting()=System.IO.Directory.GetFiles(temp)
dim i as integer[code].....