I have been using linux for quite some time now and untill now haven't been stuck..but now I'm stumped

I have a linux mail server (Red Hat 7.0) which has been up for close to a year with no problems. It also serves as the front end for an internal network of a dozen or so mixed machines (useless information) I frequently telnet to it from the outside with no problem. two days ago it started this behavior. when ever I telnet to it it allows me to login, gives me the last login date, says I have mail.. then I'm disconnected....I only have one user besides root, the one I have been using to telnet to it. SSH does not appear to work either, though I might not of ever turned it on.
I have not tried to drag a monitor and keyboard to the box, mostly out of lazyness. but i'm sure i'l have too. I was wondering if anyone has experienced this and what settings I need to change, or look at

thanks

I'm not sure if i've understood you correctly, but did you say that you have been telneting in to the box as a different user, and not root? Have you been able to successfuly log in as root in the past?
If this is correct, then I'd venture you are not able to log in as root remotely because of security restrictions on the system. PAM or one of the other features is blocking root. If this is what is happening though, then I am clueless as to why it is telling you the details on new mail, etc. before closing connection. Maybe log in as the other user and check the system logs, etc.

I was consistently able to log in via telnet normally as regular user (redblur) then at some point over the past few days..It stopped allowing me too..it would except my password..give the notification of mail. then it would disconnect....If i needed root usage I would telnet in via user (redblur) and then su to root. but that's not the issue..

thanks for the help