One Time Installation Details

Lecture123 requires a set of one time installation steps. The instructions can vary depending on the the operating system on your computer and what is already installed. This page also provides basic troubleshooting tips. Please use the quick links below or start reading the Overview section.

Quick Links


Lecture123 applications are Java based and require your computer to have the Java Runtime Environment (JRE) available for free from Sun Microsystems. The JRE provides the software foundation allowing Lecture123 to run on any computer.

Minimum System Requirements

One Time Installation Instructions

Lecture123 Installer for Windows

Please visit the One Time Installation page for instructions.

JRE Installation

The Lecture123 applications run in a Java environment which provides platform independence. This allows you to run the programs on most any computer.

Installation of the JRE on Windows typically requires administrative privileges.

Lecture123 requires Java Runtime Environment (JRE) version 1.5.0_01 (aka 5.0) or newer. Remove all old JRE installations (note: if you get an error when launching a Lecture123 application and the details refer to xerces or libs.jar, then you have an old version of the JRE that must be removed and updated). See the uninstall instructions below. In WinXP this is accomplished by going to Start > Control Panel > Add or Remove Programs. Scroll down to Java Runtime Environment, click on this entry, and then click on Remove. Do the same for Java Web Start if you see an old version.

Earlier releases of the Lecture123 software instructed users to install Sun's JMF. Please uninstall the JMF. Windows users: Start > Control Panel > Add or Remove Programs. Scroll down to Java Media Framework (JMF) and click on Remove.

If Lecture123 applications will not start after installation, then it is possible that you will need to configure proxy settings. Please read more about proxy access.

JRE Installation Steps

Mac users please follow these instructions.

Windows and Linux users please follow these steps:

  1. Go to Sun's Java 5.0 download web site.
  2. Click the Download button for "Java Runtime Environment (JRE) 5.0
  3. Accept the license agreement and click "Continue" (read it you wish).
  4. Click on the link under the heading for your computer's operating system (e.g. "Windows Platform"); use the offline installation if there's a choice.
  5. Save the download file to your local hard disk
  6. Once the appropriate file has been downloaded follow the instructions below depending on your operating system


Just double click the downloaded file(s) and step through the installation. Given the choice of Typical or Custom, it's best to select Typical. Please restart your system if the install program asks you to do so. You may delete the downloaded install file(s) once the installation is complete. You may also delete the Java Web Start icon on your desktop if you wish.


Follow these instructions to install the JRE on Linux systems:

Windows Troubleshooting

Internet Explorer Issues
Uninstalling Unsupported Windows Java Environments

At times we've seen the Lecture123 tools malfunction if there's more than one Java software environment on your computer. Please try to delete any Java programs installed on your system other than versions 1.5.0_01 (aka 5.0) or newer.

To uninstall Java installations click on the start button on the bottom left of your Windows desktop. Then click on Control Panel and then double click the Add or Remove Programs icon in the Control Panel window that came up. Scroll down until you find the J's (it's in alphabetical order). Look for any program entries in this list that are Java that are not 1.5.0_01 (aka 5.0) or newer and click the Remove button for each one.

If you mistakenly remove all Java installation, then simply run the Lecture123 Installer for Windows again.

Proxy and Firewall Access

Network Firewall

Lecture123 client applications all communicate with the Lecture123 servers using only port 80 which is the port typically used by HTTP traffic between your web browser and a web server. As such, firewalls are usually configured with port 80 open and Lecture123 should work without any firewall re-configuration.

Personal Firewall

The default behavior of many personal computer Personal Firewall programs (e.g. BlackICE, McAfee, Norton, Sygate, ZoneAlarm, etc.) is to block Internet access to applications on your system (note: the firewall that comes with Microsoft WinXP/SP2 does not block program access by default; more details about the Windows Firewall are here).

One quick method to see if a Personal Firewall is blocking execution of the Lecture123 programs is to disable your firewall and attempt to run the program again. If this works, then re-enable your firewall and follow the instructions in the remainder of this section to permit access to Java (from Sun Microsystems).

The first time you attempt to run any Lecture123 program, your Personal Firewall will likely display a window asking if it is OK to allow access. This access is being granted to Java Web Start (aka java, javaw, java.exe). If asked, you should grant access and do so on a permanent basis, e.g. "permit all" or "permit always". Beware that you might have clicked through this initial window without reading the details and actually accepted a setting that always blocks Java. In this case Lecture123 programs will be silently blocked: read on...

If you don't recall being prompted by your Personal Firewall, then please start your firewall program and get to the point where there's a list of programs being controlled. If you see any Java programs (e.g. javaw, javaws, java.exe), then please grant access by selecting something like "permit all". If you do not see any Java programs, then please add Java to the allowed program list (typically you need to add the executable file javaw.exe and/or java.exe in the C:\Program Files\Java\jre1.5.0_XX\bin folder (where XX is the sub version, e.g. 10). You may also need to add the file javaws.exe in the C:\Program Files\Java\jre1.5.0_XX\bin\javaws folder

Please consult your Personal Firewall documentation or web site support for further assistance. If you are still experiencing problems, then please email the Lecture123 Support Team.


If you get an error when attempting to run a Lecture123 program, e.g. an HTTP 404 error, then you may need to configure proxy settings on your computer. If you get an HTTP 407 error, then you likely use an authenticated proxy server and must configure your proxy user name and password in Lecture123 as per instructions below.

Lecture123 client application use Java Web Start (JWS) from Sun Microsystems (the Lecture123 installer installs JWS if your computer does not have the appropriate version). The default for JWS is to use any proxy settings that are configured in your web browser. If your access to the public Internet uses a proxy server, then you (or some software you have run) have likely configured the proxy server settings in your browser.

JWS Proxy Details

More detailed information about JWS proxy settings are found in the J2SE 1.4.2 Java[tm] Web Start Technology README.

Browser Proxy Settings

Typically you will change the setting from using a direct connection to a proxy server configuration. Here are instructions; please check the specific instructions provided by your web browser:


We are here to make your use of Lecture123 simple and successful. Please email any bugs, feature requests, or documentation issues to the Lecture123 Support Team.