Same problem here. I've been testing a couple of hours (6 hours at least, thank god there's VmWare). I've been able to narrow it down to ohotfix.exe as well. I do an unattended install of WinXPSP2 build with RyanVM updates and the updates supplied by Driverpacks.net (KPD for all drivers enabled). WPI starts as the last command in RunOnceEx. When I select Office 2003 Pro (full options) and Service Pack 2 updates, at the end of the Service Pack 2 updates I get the same error (same line numbers, so probably not related to config.js or rb_config.js). Just before the error appears, the WPI progress box turn to white (only the top bar with the three buttons at the right is visible). SP2 is still updating at that time. The progressbar will fill up 1 more time, completely (starting at 0%). After that the process hangs. My SP2 directory contains mainsp2ff.msp and the three ohotfix files. The entry in WPI consists of three commands. The first and third are a "%sleep% 30". The second is "%wpipath%\Install\Office2003ENUpd01\ohotfix.exe" (whitout the quotes). There are no spaces in %wpipath%. It appears that at the end of SP2 a process runs that conflicts with WPI. I don't know if anyone can disect .MSP files to see what the potential problem is? Running from a USB stick I haven't encounterd any problems for at least a year, probably more. BTW, ohotfix is included in every full-download-hotfix for office, just extract with your choice of compression tool (Winzip, WinRar, whatever). Ohotfix.ini might need some tuning before it works the way you want it.