>>>Hi
>>>
>>>Will it cause problems if I restart SQL server.
>>>
>>>ie do users need to disconnect before I do it ?
>>>
>>>The Server mchine is running very slowly and I wonder if this could be a quick fix.
>>>
>>>Thanks
>>
>>:)
>>
>>Well, at least disconnect all the users first (let them know you're going to re-start the server).
>
>Whats is the best mechanism for telling the users you are going to have to restart. Is there a facility in the management studio.

Well, the simplest is to use NET send command.

I've googled a bit and found this blog
http://weblogs.sqlteam.com/mladenp/archive/2008/07/18/Immediate-deadlock-notifications-without-changing-existing-code.aspx

Anyway, it's not something simple you can do from SSMS.