I would advise caution whenever someone chooses to restart the server.  That should only be done as part of an install process or as A LAST RESORT during configuration changes. 

This is especially true with Windows Server 2003, where you can perform a lot of the administration that may have required reboots in the past.  Although there are always exceptions, this shouldn't be one of them.  Restarting IIS essentially clears out all application and session information by recycling the worker process (among many other things).  This is the goal behind recycling the application pool.  We simply want to clear out the cache of the DNN site.  This is not always possible by browsing to it as "host" in this specific situation.

As a general rule, unless you are an Administrator of the network, I wouldn't advise that you ever restart the server.  There are many potential conflicts that may arise out of restarting the server that you may not be aware of.  In the end, if your Admin is worth his/her salt, they will know within seconds if you rebooted the server anyhow.

I am not trying to step on what you said aashutoshSAKA, but rebooting servers is not a good practice like it used to be.  Although rebooting it in this situation will have the same end result, there are many new problems that may or may not arise from doing so which may not affect the web applications, but may certainly affect things on any network that the server may be on.