Issue related to Windows 2003 server

Hello,

I am working on Windows 2003 Server. It is loaded with Oracle9i and Java also. It is an OLTP server.
When I try to open any file during office hours to prepare some report ( EX: If I try to open MSDOS prompt, msword, Notepad, mspaint) it will not respond, it will get stuck at that point.

If I restart the server then everything will work properly.

This problem happens frequently (say 2 t0 3 times a day)

Server is updated with all the recent patches, and there is no problem with Hardware

Could anyone suggest me the appropriate solution for this problem.

.