Because some scripts may take an excessive amount of time to run, Internet Explorer prompts the user to decide whether they would like to continue running the slow script. Some tests and benchmarks may use scripts that take a long time to run and may want to increase the amount of time before the message box appears. In Internet Explorer, the script time-out value can be changed on specific client machines by modifying a registry entry.

There are situations when a Web page contains script that takes an unusually long time to run. If you are scripting an ActiveX control on a Web page to transfer a very large file or do a large database query, this will often cause a significantly long delay. Internet Explorer 3.02 detects the long delay and prompts the user with a dialog box reading the following: The equivalent message box for Internet Explorer versions 4.0, 5.0, 6, and 7 reads: This mechanism allows the user to stop misbehaved script that runs into an endless loop or otherwise is performing slowly.

In Internet Explorer 3.02, this message box can appear on machines running Windows 95. The version 3.02 browser is specifically looking to see if the script thread has pumped any windows messages in the last five seconds. There is no way to override this time-out period for Internet Explorer 3.02. If you are using an ActiveX control with long blocking operations, that ActiveX control should either employ an event mechanism and return control to the caller or call PeekMessage every five seconds to reset the time-out.

As of Internet Explorer 4.0, 5.0, 6, and 7, the time-out is no longer a fixed value based on Windows messages. Internet Explorer now tracks the total number of executed script statements for the current page with the script engine and throws up the time-out dialog box when that value hits a threshold amount.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

To change this time-out value in Internet Explorer 4.0, 5.0, 6, or 7, follow these steps:

1.	Using a Registry Editor such as Regedt32.exe, open this key: HKEY_CURRENT_USER\Software\Microsoft\InternetExplorer\Styles Note If the Styles key is not present, create a new key that is called Styles.
2.	Create a new DWORD value called "MaxScriptStatements" under this key and set the value to the desired number of script statements.

By default the key doesn't exist. If the key has not been added, Internet Explorer 4 defaults to 5,000,000 statements executed as the trigger for the time-out dialog box.

Because the Internet Explorer 4.0, 5.0, 6, and 7 time-out is based on the number of script statements executed, the time-out dialog box will not display during ActiveX control or database-access delays. Endless loops in script will still be detected.