Microsoft Outlook 2003, up to and including the most recent Microsoft Office 2003 Service Pack, has an issue with custom forms that typically manifests with the error message: "Outlook cannot open this form." Unfortunately, no other real details are provided as to why that is the case.
The culprit of this problem is probably a polluted Microsoft Outlook's form cache that needs to be cleaned out.
This can be done from within Microsoft Outlook itself, but it requires a fair amount of drilling through menus to get to the needed commands. It also has to be done differently if you're using a local .PST file or an Exchange Server public folder, which complicates things yet further. If you're forced to clear the Microsoft Outlook forms cache repeatedly, it becomes even more cumbersome.
Fortunately, Microsoft Outlook MVP Robert Sparnaaij has created a script, written in Visual Basic, that automatically clears the Microsoft Outlook forms cache.
When run, it'll prompt you to close Microsoft Outlook (if you don't, it'll make a best attempt to close Microsoft Outlook by force!), and then erase the files in the path %UserProfile%\Local Settings\Application Data\Microsoft\Forms, which is where the Microsoft Outlook's forms cache is stored. The folder is also deleted for good measure, in the event that there are problems with the forms cache folder because of permissions issues.
Note that if you run this script on a system with an antivirus application that provides live protection, the antivirus program may attempt to stop the script from executing.
About the author: Serdar Yegulalp is editor of the Windows Power Users Newsletter.
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