FIPS Error - Excel Export

[Raphael]

Hello everyone!
The main functionalities  of my Website are to show and export (PDF & Excel) reports with a reportViewer of Silverlight. The reports are generated on the server side via WCF services. 
PDF Export works fine, but every time the Excel export is used, it generates an error (see screenshot).
I think the whole error message is: 

"This implementation is not part of the Windows Platform FIPS validated cryptographic algorithms"

I tried to: 

• apply the microsoft patch here, but it isn't a compatible Windows version.
• reproduce the problem and changing the regedit values to true (explained here), couldn't reproduce it.
• change the web.config file, and forcing the FIPS policy to false (explained here)
• change the web.config file and add a new machineKey section (explained here)

None of these worked. I hope you could help me out. Any ideas for that problem?
Thanks
Raphael

PS: I am using the version Q3 2011 SP1 of Telerik Report 

[Raphael]

Hello again,
We found a workaround (solution 2 on my post before). We disabled the Fips Algorithm Policy. 

• [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\FipsAlgorithmPolicy] "Enabled"=dword:00000000

On the server machine (and rebooted).
Now it works.

Anyways, I would be glad to know why this happened. And if the export would work with that Fips Algo Enabled?
Thanks
Raphael