In general, web conferencing systems demand quite a bit from your computer. As with all applications, sometimes the additional work required of the web conferencing system combined with the affects of undetected malware will tax a computer to the point of producing errors or causing a crash.

Quite often unbeknownst to the user, a computer virus, or other malware will have unintentionally been allowed to infect a computer, and will use resources of the computer in such a way that a demanding application such as a web conferencing system will be unable to function within this environment even when all other things you normally do on the computer seem to work fine.

Fortunately, Microsoft has developed a tool which is designed to scan and remove an extensive list of malware from your computer. The "Malicious Software Removal Tool", or MSRT for short will remove most of the bad stuff from an infected computer. The MSRT can be downloaded for free from Microsoft's web site at http://www.microsoft.com/security/malwareremove/ .

Microsoft includes this tool as part of their monthly Windows Updates. When run as part of Windows Update it's sufficient to keep a known OK computer healthy, but the scan it makes is not as exhaustive as when run standalone. If you are experiencing problems it's best to run it by itself in it's most thorough scan mode. A new version of this tool is released almost every month and best practices dictate that you run it just as frequently.

It is also important to make sure you keep your computer updated with Microsoft Windows Update, this will ensure your computer has the latest bug fixes and security updates.

First, make sure you have all of the latest Apple updates installed.
Once you have the Mac updated with all of the available updates, see this article to solve the crashing issue when trying to present using GP4 or GP5.