Could you provided us the full stack of the NoClassFound error in order to know which class is missed.
Please let me know if you have any solution on that. I am using 126.96.36.199.
of which product ?? Forms Reports Services, SOA, UCM etc
What it's you Windows version, architecture, java version ??
Do you have other Oracle product installed in that computer ??
Check the log file under domain_home\servers\server_name\logs\xyz_server.log for the complete stacktrace of the error and share it with us for investigating the cause behind the issue.