You might also check your transaction log file(s) and see if they have unrestricted growth. If so they can become resourse hogs very quickly. Set up a maintenance plan...

Here's one for 2005. I'm working with 2005 but i've used these pages for help before so there can't be much of a difference. I also thought the 2008 insturctions...

The msdn covers this topic pretty well:

http://msdn.microsoft.com/en-us/library/ms141091.aspx

http://msdn.microsoft.com/en-us/library/ms141711.aspx

Enjoy

I just finished reading an article on this yesterday:

https://blogs.msdn.com/bwelcker/archive/2006/08/14/700189.aspx

We lost it with SP1, but currently there is a patch and it should be back with the next SP.

Just a stab in the dark, but try removing 'Public Shared' and just go with 'Function ReportTotal....

Just as an update, everything I've found said that it couldn't be done.  I scraped the Reporting Services report and used the excel program interop assembly and coded the project...