delay in VB

Hi all,
I am using Shell command to unzip a file but as it takes more time the execution proceeds to next line where i am checking whether the unzipped file exists or not? So eventhough the file is there is shows me that the file is not found. So can anyone help me in how to give a delay after shell so that first all the files are unzipped and then the execution proceeds to next line.

To solve this ----------
I have used a variable which stores current minutes + 2. Then i am executing the shell command and after that i am executing a loop till current minutes become equal to that variable but this consumes the CPU time and memory and as it has to be run on Server this is not proper.

So please if someone can give me other alternative to do this. Its very urgent
Any help will be appreciated

Thanx in advance