I have a HP server with windows server 2003 and 50 windows XP clients. Since a week and a half the networks speed suddenly drop 2-3 times per day. It gets so slow that none of the clients could work with the HIS program installed on them. We tried so many different things such as replacing the hubs,switches and even some wires. Every time one of these changes solves the problem and the network goes back to its normal state. I checked everything. Even when I disconnected all the clients from the server and connected it to just one computer the problem still remained for 2 hours. I just narrowed down the problem to the couple of likely speculations as follows: viruses? (Updated Kaspersky running on the server shows none) server hardware failure? Physical memory usage on the server? (Because the last time the problem occurred none of the changes above solved the issue so I restarted the server an checked the physical memory usage which was 2 GBs. But I noticed it's increasing over time to over 9 GBs...the server has 16 GBs of RAM.) I surfed the internet and got nothing. Any help would do us a lot....thanks in advance