This issue came up for me this week so I thought it might be helpful to provide the solution. I obtained the solution below from CustomerEffective’s Blog and am applying it now.
"Unable to Load Client Print Control" message when printing CRM v4.0 reports
Issue: When clicking the Print icon to print a CRM v4.0 report (in a SQL Server 2005 database) you receive the message "Unable to Load Client Print Control" and the report does not print.
Cause: Windows Security Update KB956391, an automatic security update. Once installed it causes the issue above with Windows Server 2003, Windows XP, and possibly others. Windows Vista machines do not appear to be affected.
Solution: Install the fixes below on the necessary servers and reboot each server.
Microsoft Report Viewer Redistributable 2005 Service Pack 1 http://www.microsoft.com/downloads/details.aspx?FamilyID=82833f27-081d-4b72-83ef-2836360a904d&DisplayLang=en
Security Update for SQL Server 2005 Service Pack 2 (KB954606) http://www.microsoft.com/downloads/details.aspx?FamilyID=4603c722-2468-4adb-b945-2ed0458b8f47&DisplayLang=en#filelist
SRS Server (if separate from SQL):
Apply the same update for SQL Server to the SRS Server if SQL and SRSS are on different machines. See the link for SQL Server above.
The next time a client prints a report, they will be prompted to install a new version of the view control. Just click install and the Print window will open.