We have all probably had experiences with computer viruses . . . those nasty things that corrupt files — if not entire systems. But with a little understanding of how these viruses function and spread, we can protect our important files — like our multimedia presentation files — and save much wasted effort and heartache.

What Are Macro Viruses?

One of the most common and harmful types of viruses, is a "macro" virus. A macro virus is self-replicating code written in an application's macro language. The keys here are "macro" and "self-replicating". Many common applications, such as Microsoft Word, contain macro capabilities. (For example, take a look at the Tools > Macro option on the Word menu.) However, the distinguishing factor that makes it possible to create a virus with a macro is the "auto-execute" macros in a language. An auto-execute macro is executed in response to an event — and not necessarily in response to a user command. Common auto-execute events include things like opening files, closing files, or simply starting an application. So, a macro virus can infect an application automatically. And, once a macro virus is running, it can copy itself to other documents, delete files, and even corrupt a user's entire system.

Protecting Files from Macro Viruses

The key to protecting many files — including PowerPoint files — from viruses is establishing an appropriate security level within the specific Microsoft application.

Word, Excel, and PowerPoint Security Levels

Fortunately, you can set the security level for many Microsoft applications — Word, Excel, and PowerPoint to high, medium, or low. The default security level for Excel and PowerPoint is medium, and the default security level for Word is high.

• High Security
  This security level ensures macros must have digital identification stamps indicating the macros have not been altered. If these identification stamps are not present, PowerPoint automatically disables the macros without notice.



• Medium Security
  This security level prompts you to enable or disable macros when you open a PowerPoint file. Of course, it is recommended that you disable a macro if you do not know who created it.



• Low Security
  This security level means that PowerPoint does not perform any macro checking functions when you open a document. Macros are enabled automatically. This security level is not recommended.

Setting a Security Level in Office 2000

If your administrator has not enforced a security level for your organization, you can change the security level for Word, Excel, and PowerPoint at any time when working in these programs.

To set the security level in PowerPoint 2000

1. Open PowerPoint.



2. Select Tools > Macro > Security.



3. Click the Security Level tab, and then select a security level.