Tim Mackey's Weblog

if, like me, you were running VS 2008 Beta 2 on a server and you had crystal reports working fine, and then recompiled your projects in VS 2008 RTM, you may get an error like this when you try and create a crystal report on a production server:

System.Runtime.InteropServices.COMException (0x800736B1):
Retrieving the COM class factory for component with CLSID
{5FF57840-5172-4482-9CA3-541C7878AE0F} failed due to the following error:
800736b1. at CrystalDecisions.CrystalReports.Engine.ReportDocument..cctor()

In my case, i had installed Crystal Reports Runtime for VS 2008 Beta 2, and i never installed the runtime for the RTM version.  it should be available on your VS machine, if you opted for CR in the VS installer:
C:\Program Files\Microsoft SDKs\Windows\v6.0A\Bootstrapper\Packages\CrystalReports10_5

should probably uninstall the old version of the CR runtime while you're at it too.