old core.js file???

Currently down in Charlotte at the MSFT campus this week getting educated at 'SharePoint RockStar' class. SharePoint RockStar is a MSFT internal class that does a deep, deep dive into SharePoint at the 300-400 level on subjects, such as the SP Core, Search, Performance, Authentication, User Profiles, etc. Needless to say, the content is massive!

Issue:

Had a customer ping me with an issue early this morning... Seems they did some upgrades to their system recently.. as in upgrading to the August 2011 Cumulative Update for WSS 3.0 & MOSS 2007.

Since doing this, they now have issues with people who are trying to create/complete workflows, the message "Sending data to server" appears on the screen and just hangs, not allowing the workflows to advance. 

Also, getting the following Warning in the event logs.

Event ID: 5368 - Exception occured during the reuqest processing. (Type: InfopathLocalizedException, Exception Message: The security validation for this form is invalid.)

The updates they installed were:
Office2007-kb2508964 - MS11-074 SU
Office2007-kb2553001 - MS11-074 SU
Office2007-kb2553002 - MS11-074 SU
Office2007-kb2553003 - MOSS 2007 MS11-074
office-kb2553020 - MOSS 2007 Aug 11 CU
wss-kb2493987 - MS11-074 SU
wss-kb2553022 - WSS 3 Aug 11 CU

Troubleshooting:

Check the core.js files in these 2 folders:

C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12 \TEMPLATE\LAYOUTS\INC
C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\LAYOUTS\1033

Resolution:

Fortunately, they had a development farm that they also pushed the same update on for testing a few days ago that didn't have the issue. They compared the core.js files on the 2 servers and noticed for some unknown reason, the core.js files did not match the ones that were on the development server. They ended up saving a copy of the old core.js file and copied over an updated core.js file from the dev server to replace the old on. After an IISRESET, the issue disappeared...