unresponsive server

[abstech]

Our digidelivery (not sure if its LT or GT) will, at times, become very slow when a client is downloading files, and then will drop the client, and then become compleatly unresponsive, allowing no admin or client logins. To fix the situation the server has to be shut down, and restarted w/all network connections disconnected. it will then act normally for a few days and then this will happen again.

We are running the lates software (2.1.1). Any ideas?