Heads Up! KB2597166 - Causes Excel to break badly.
Good old Microsoft does it again with the Security Update for Excel KB2597166 MS12-030: Description of the security update for Excel 2010: May 8, 2012
Once this gets on to your systems you can expect Excel to start crashing, memory Errors, Unable to Save, Random sensless prompts and messages, System comes to a standstill with locked up screens and all sorts.
I have Win7 64bit workstations and 32bit Office and it busted all of them. Uninstall and its fixed instantly.
They have know about the bug since release on 08/05/12 but have yet to resolve the issue.
You can decline the update in WSUS and set it for removal which I have just done as I manually removed it from a load of machines yesterday and it re-installed itself again today and I started to get a load of complaints again.
Nice to know its not just me MS has it in for!
This update stopped Excel from even loading on my workstation, which I documented on my blog (which I can't post a link to).