This is also problem with an install of QuickBooks onto a Windows system!!!!
Solution can be found here:
http://windowsxp.mvps.org/ie/qbooks.htm
...but in case the link dies,
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When you launch QuickBooks software, you may encounter the error "This version of QuickBooks requires Internet Explorer 6.0", even though you're running Internet Explorer v6.0 or above. This error is misleading and the problem is due to a missing or incorrect App Paths value in the registry. The App Paths value in 8.3 format is the major cause. (Thanks to Mr. Mike Reed for submitting this information via email)
RESOLUTION
Click Start, Run and type REGEDIT. This opens the Registry Editor.
Navigate to the following location:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\App Paths\IEXPLORE.EXE
Backup the key by exporting it to a REG file. See here for more information.
In the right-pane, double-click (default) and type-in the full path where Internet Explorer resides (usually C:\Program Files\Internet Explorer\IExplore.exe). Don't type the value in 8.3 format, it should be in Long File Name format. If IExplore.exe key does not exist, create a new key and complete the above procedure. Restart Windows for the changes to take effect, and then launch QuickBooks. The error should no longer be seen.
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Note that Quickbooks appears to have problems with any version of IE other than v6. Fortunately, IE6 is available on the Quickbooks CD. This tip got me past the error, but I still can't get a completely clean install of this application.
Another potentially useful link for ie6 problems:
http://www.quickbooks/support/ie6
Information courtesy of http://www.anothermouse.com/