PhStat2 Statistical Add-In for Excel 2003

The operating system on my notebook is Vista home basic and I have installed
PhStat2 statistical add in tool for excel 2003. It worked for a few days then
stopped working. Now I get "Automation Error; Unspecified Error". clicking on
help on this information gives more detail on this error :
"Automation error (Error 440)

When you access Automation objects, specific types of errors can occur. This
error has the following cause and solution:

An error occurred while executing a method or getting or setting a property
of an object variable. The error was reported by the application that created
the object.
Check the properties of the Err object to determine the source and nature of
the error. Also try using the On Error Resume Next statement immediately
before the accessing statement, and then check for errors immediately
following the accessing statement.

For additional information, select the item in question and press F1 (in
Windows) or HELP (on the Macintosh)."

I have this add in tool installed in a desktop with XP Pro and works
seamlessly. I am not an advanced user of excel nor a programmer. If there is
any walk-thru solution, please help?

Thanks

Debanjan