Had a couple of Small Business Server (SBS) 2003 boxes throw up blank daily monitoring reports recently. Most servers have been ok apart from these two, both SBS 2003 R2 with WSUS 3.0 SP1. One's a home build basic PC spec and the other is a Dell PowerEdge 860 dual core with 2GB RAM.
I wasn't able to get a fix despite trying reboots, updates, disk checks, reconfiguring monitoring, SQL database checks, etc. Got a fix now thanks to advice from Les Connor a Canadian SBS MVP, see the link here.
Basically you need to go into the main WSUS console (from Admin Tools) then Options and Server Cleanup Wizard. Running this with just the first option for Unused Updates fixed both servers. The PowerEdge took 18 hours to complete - reporting unused updates 11,092 and revisions 3,830. Sounds like this WSUS maintenance needs to happen on a monthly/quarterly schedule to keep the server optimised.
The basic server crashed out at 19 hours with SQL timeout errors. The monitoring report didn't come back immediately, until after a reboot.
Both are happy again ... me included :-)