Client Machines Logon to SAP Server is Very Slow

Hi Experts

last one week onwards,Client Machines to connect server it's taking TWO Minutes time .(Earlier it will was connect with in seconds)

What are the  causes??

I Done follow steps server side as well as Client also

1)Temp File Removed

2)Pref etch  File Removed

3) Recent Temp File Removed

4) C Cleaner Run

5) No One is Running LONG Reports

and Then also same...Even i log in Server also it's Took 2 Minutes Time

Server is IBM Rack Server GOOD Hardware Configuration

Thanks&Regards

AndakondaRamudu