This "bug" affects only Dell laptops with Media Direct. This is really not an Outlook bug - it's caused by an add-in Dell ships with their laptops that support Media Direct.
Dell laptops include an application called Media Direct and this application installs an Outlook add-in called "Outlook Setup Addin" (outlookaddin.dll) which causes problems for some users. This add-in supports the Instant Office feature of Media Direct. Uninstall it from Control panel, Add and Remove Programs to prevent the problem with future meeting requests. You can also disable it in Tools, Options, Other, Add-ins (Outlook 2003) or Tools, Trust Center, Add-ins (Outlook 2007).
Along with causing meeting requests to become recurring, it doesn't work well with Outlook 2007 and is responsible for at least some of the complaints about Outlook 2007's slowness and CPU resources spiking.
This add-in is responsible for creating Calendar folders in My Documents when you work with attachments.
What is MediaDirect?
What is MediaDirect and Instant Office? Media Direct lets you play DVD's without booting into windows. Instant Office is a way to quickly view certain items on the computer when the computer is powered down. It's a pretty cool idea, too bad it doesn't play nicely with Outlook.
Description of the MediaDirect feature taken from the Dell website:
Dell Exclusive: MediaDirect featuring Instant Office Dell MediaDirect puts your media and more at your fingertips. Now it also gives you "instant on" access to your calendar, contacts and presentations. With the computer off, one press of the MediaDirect button gives you quick access to items on your hard drive, optical drive, a USB key or from the integrated 5-in-1 media card, including:
"Instant Office" featuring Microsoft PowerPoint Viewer, Microsoft Outlook and Outlook Express Calendar Viewer, and Microsoft Outlook and Outlook Express Contact Viewer